What a serious difference in pricing. And they are not some fly-by-night eBay dealer either. Any idea why?
Mouser $59.09 http://www.mouser.com/catalog/catalogusd/646/2321.pdf
DigiKey $52.18 http://www.digikey.com/product-detail/en/24-6337-8800/KE1400-ND/61656
All-Spec $22.85 http://www.all-spec.com/products/KW24520.html
Priced to make money.
The more reputable you are the less likely people will question your pricing on the random low volume stuff.
The other one might just be trying to get ride of it.
I've noticed that Mouser and Digi-Key don't like carrying certain products. They seem to do it solely as a convenience to their customers. And, as you've discovered, they charge a significant premium for that convenience.
TechniTool has the lowest price?! That's unexpected!
.031" is kinda thick.
I'd go with thinner, 0.025"
This is what I use
purchased locally.
Wash boards off with 99.9% anhydrous isopropyl when done.
CrossRoads:
Wash boards off with 99.9% anhydrous isopropyl when done.
http://www.mgchemicals.com/products/cleaners/electronic-cleaners/isopropyl-alcohol-824/
Does this give a clean board ?
I dont use that particular solder but have a hard time with residue.
Rosin flux base.
Do you ultrasonically clean ?
Nope, just a stiff brush with the alchohol.
Removes any rosin residue from around the pins.
Not to disagree in any way, but another factor that may be in play is the fluctuation in the price of metals. I'm not even sure what the market for tin and lead has been like lately, but in the past there have been significant short-term variations. Maybe Digi-Key and Mouser don't like the high maintenance (can't blame them) and so they set the price above the fluctuations.
CrossRoads:
Wash boards off with 99.9% anhydrous isopropyl when done.
http://www.mgchemicals.com/products/cleaners/electronic-cleaners/isopropyl-alcohol-824/
There is zero need for that level of purity and it being anhydrous. Let alone the fact that I can more or less GUARANTEE that it is not 99.9% anhydrous after the firs time the bottle is opened (if it even is by the time it reaches you). Alcohols will actively pull water out of the air. Maintaining an anhydrous alcohol solvent is not easy. Typically, it requires at minimum packaging over molecular seives. This is not something that is just conjecture or theoretical. As an inorganic materials science chemist, its something that I deal with regularly. From the prices I see, the purity level is a bit suspect as is the anhydrous claims. That being said, its still a solid price for a high enough purity for the intended use.
PedroDaGr8:
There is zero need for that level of purity...
Maybe. The flip side of the argument is the risk of using alcohol that's been adulterated. I assume run-of-the-mill rubbing alcohol will contain things that could leave an undesirable residue, damage exposed metal, or damage plastic parts.
...and it being anhydrous
No argument there. What's the point of removing nearly every trace of water just to add it back in?
I find it stays "drier" then the 95% stuff, and dries faster after a board is cleaned, even if some atmospheric moisture is absorbed back in.
Denatured ethanol (in gallon cans from Home Despot or similar) works well for me. Drying the boards with compressed air or a hair dryer makes short work of the small bit of water the alcohol picks up. When using a hair dryer, I keep the bulk of the alcohol away from it and shake most of the alcohol off the boards first, just in case.
CrossRoads:
Wash boards off with 99.9% anhydrous isopropyl when done.
http://www.mgchemicals.com/products/cleaners/electronic-cleaners/isopropyl-alcohol-824/
+1 on this, since we are discussing it. They sell it at Fry's and all I know is that it works really well.
AFAIK, you don't actually need to wash rosin off at all, short of cosmetics and some ultra-sensitive circuits...
The only (electronics) fluxes you need to wash off are the ones designated "water soluble" but NOT "no clean."
westfw:
AFAIK, you don't actually need to wash rosin off at all, short of cosmetics and some ultra-sensitive circuits...
The only (electronics) fluxes you need to wash off are the ones designated "water soluble" but NOT "no clean."
We like our precious to be teh pretty! 
This is a good point. Typically, the impurities are mostly water plus small amounts of related alcohols such as methanol, ethanol and 1-propanol. That being said, there is NO guarantee that these are the impurities.
I would avoid denatured alcohol if at all possible. Typically, ethanol is denatured with a combination of toluene, xylene, ethyl acetate plus a few other compounds. These materials can significantly affect plastics. Recently I was making a 20% EtOH/water solution in a plastic bottle using denatured ethanol. The denaturants actually ate the plastic off of the inside of the bottle. I had to end up using non-denatured alcohol which is MUCH more expensive (even though its for chemical use we still have to pay liquor tax on it because it CAN be consumed).
As for the water taking longer to dry. For most of these, the water is bound as an azeotrope with the alcohol. This means that it evaporates off with the alcohol as one unit. This is why in distillation you can't get a higher alcohol percentage than 95%. This azeotrope actually serves to lower the boiling point of the isopropanol slightly, so it should evaporate more easily. For example, pure i-Pr boils at 82.5oC while i-Pr and water azeotrope boils at 80.4oC. If it is harder to evaporate there are likely other compounds involved (or there is an excess of water).
OK I think I have successfully hijacked this thread badly enough. I should shut up now.
I wash off the rosin because I don't like the sticky feel of the board afterwards. It also makes it easier to inspect the solder joints.
PedroDaGr8:
OK I think I have successfully hijacked this thread badly enough. I should shut up now.
Haha, it's good, we like chemistry 
Hi, we go through litres of isopropyl alcohol at work to clean PCB after assembly or repair so they can be sprayed with Conformal Spray.
Its good stuff, we had a salesman around the other day (they supply or iso) with a product that is supposed to be better than iso, it was marginally better but we could not see any cost saving advantage.
It did not leave any staining or marks behind, but just to expensive.
As for prices, try RS and Element14, some prices different by factor of 4 or 5.
Try a E14 part number in RS and you get the RS equivalent part if available.
Try RS part number in E14 and you get E14 equivalent part if available.
Most times part in each case is exactly the same, only cost is different.
Tom...... 
Mouser and Digikey may provide traceability and quality assurance paperwork for customers that require such things.