A PIC is a microcontroller. Microcontollers are an entire computer( memory, CPU, storage space, timers, etc.) crammed into a single chip. MOst low cost microcontrollers cost between $2 and $10 depending on what features they have.
Microchip.com is the website for the company that makes the PIC. Other Microcontrollers to look at are the AVR made by Atmel, the Z8Encore made by Zilog and the 8051 which is made by a lot of companies (Silicon labs has my favorite though silabs.com).
I'd recommend buying a development kit for which ever one you choose - it will save you a lot of headaches and thay arn't that expensive. Z8F08200100KIT (the Z8Encore) is $39 on digikey.com I've heard its a great kit. ATSTK500 (the AVR) is also a good kit though it can be a pain to get started (also available on digikey.com). The ASTK500 also works as a device programmer which is nice.
Hope this helps
Brent