I recently thought about building another purpose-specific 6502 SBC.
I'd like to have a sizeable keypad and a simple alphanumeric display. Those parts I'd have to buy. At least the keypad, I may have a display I could use.
I thought about these:
http://www.ebay.com/itm/231598548744In the distant past, I've thrown quite a number of them in the trash due to physical damage, or just the owner wanting to do something different. I never tried to keep one, as I always assumed other people would be throwing them out too, and if on the odd chance I'd ever need one they should be easy to get second hand. But apparently they are selling for more than I expected. That one is $50 but I see some selling for $300 and up.
These things have a Rockwell 6502, a fair amount of RAM, and a good amount of I/O. I wish I had tried to keep some.