"If you were looking to acquire the first microprocessor for your collection, or just to show it to your friends, there is a good deal on eBay right now. You can get Intel 4004 CPU in plastic package with full set of 4004 support chips, also in plastic packages, for mere $49 from this auction. Hurry, as these chips will sell fast. Granted, the plastic 4004 CPU is the cheapest from 4004 family, but in the past just the P4004 CPU without support chips was sold for more than $50. The same seller was recently offering three microprocessors - Intel P4004, D8008-1 and P4040, which are the first and second CPUs in history, and enhanced version of the first CPU respectively. The auction lasted less than two days, during which time 50 sets of chips were sold.

Update: All Intel 4004 chip sets are gone now. The auction lasted less than 6 hours ..."