So, I'm using a solar lipo charger from Adafruit which costs around $17. The core of the charger is the MCP73871 charger + thermsistor.
They work fantastic! Having said that, I found a component on eBay that looks like the same exact circuit but only costs $3 (coming from China).
Are these components the same? I don't mind soldering all of wires directly to the board (I'm doing it anyways on the Adafruit one). If so, why is it 5x the cost? Am I missing something?
I’ve had good luck with boards from China.
I'm just wondering if there's a significant difference between these 2 boards to justify that cost. I'm ordering the eBay boards just to test.
From what I see on the photos those boards often look truly identical.
In some cases maybe Adafruit designed the board and what you see on ebay is a Chinese clone (not surprising as Adafruit open sources all their designs); it is likewise possible that Adafruit resells the Chinese made boards. I often suspect the second when I see the exact same boards pop up at both Adafruit, Sparkfun, Seeed, and sometimes one or two other such companies as well.
Thanks for the insight. I guess I never suspected a markup like that unless something was vastly different.
Faster shipping to US customers is a major advantage.
So also the packing is done by Americans receiving US level salaries, not Chinese receiving Chinese level salaries. That alone is a significant difference. And Adafruit actually seem to know what they're talking about, usually.
wvmarle:
And Adafruit actually seem to know what they're talking about, usually.
+1 for that. 
You are paying for service. Adafruit backs up their products. On eBay you are lucky to get any information regarding the device when you wait the three weeks to get it. 
As larryd says, there is little to suggest that the components are not the same, from the same factories, mounted on the same PCB material and so on. Those of us with experience can usually figure out the details (by cross-referencing and careful Google-fu) for ourselves and can - generally - cope with the lack of support.
For me, the waiting part works a little different - as it matters a lot where you live. I usually buy my parts directly from China on Taobao, sometimes had it delivered the next day (quite impressive if you order late afternoon). Usually I use the cheaper shipping methods and it's 4-6 days. Most electronics are from the Shenzhen area, so basically next door.
Once I bought a [url=https://www.sparkfun.com/products/15050sensor from Sparkfun[/url] (still can't get that one anywhere else - too much of a niche and pretty expensive), took a few weeks before it was delivered. The tutorial for that specific sensor is also a bit misleading in itself, the pinout of the sensor has apparently changed since Sparkfun built theirs, due to new firmware! Never seen that before.
For me, China (the Lo Wu border crossing, that is) is 20 minutes by train; the US is the other side of the world...