I'm currently working on some simple little projects that seem to be liked quite a bit, and I'm thinking of selling them.
The target is people who wouldn't normally buy a DIY kit online because "they don't trust the Internet" and wouldn't make their own projects because they're new to electronics.
It's stuff that lights up: Kraftwerk ties, POVs, LED "dolls" that and blink when hugging each other; really simple.
The microprocessors I'm using right now are the MSP430s value line ones, which come at about 1.50€ each. That's OK for personal use, but it would be nice to cut the cost a bit and keep the gadgets cheap...
Can we go any cheaper without having to buy huge quantities?
1.5 euros = 1.9456 US dollars (ala Google)
$1.09 each in low quantities.
Wow, that is inexpensive! Can do a lot with 6 IO - or very little, depending on your project
Digikey has ATTiny10's for even less, $0.80
Just 4 IO, 6-pin SOT23 package.
It appears that ATtiny4, ATtiny5, and ATtiny9 exist also for a few pennies less:
Device Flash ADC Signature
ATtiny4 512 bytes No 0x1E 0x8F 0x0A
ATtiny5 512 bytes Yes 0x1E 0x8F 0x09
ATtiny9 1024 bytes No 0x1E 0x90 0x08
ATtiny10 1024 bytes Yes 0x1E 0x90 0x03
Even at $2 each, "other" costs tend to dominate an actual project
The cheapest micro ever was the Atmel ATtiny11, which sold (rather briefly) for $0.25 each in quantities as low as 50 or so.
It was not a particularly pleasant thing, requiring a special programmer, and it only had 512 bytes of flash. Alas, these are no longer available (I think Atmel was basically selling off stock at fire-sale prices...)
For approximately $0.50, there are a number of choices, including some of the PIC16F chips that started (sort of) the whole "tiny microcontroller" craze. PIC16F54 is an 18pin chip with 512 instructions of flash, and there's a pretty broad range of pincounts available at similar prices.
Freescale is also a contender with some of their MC9RS08 chips, though they don't have a very good reputation in the hobbyist venue (they look like nice chips, though.)