If you are looking to build a decent budget HTPC, Newegg is having a sale on a combo that isn't bad.
Combo comes with Mobo, CPU and Ram.

All you need now is: Case, PSU, HD and optical Drive to complete the build.
You can probably build a entire HTPC for under $300

MSI A55M-P33 FM1 AMD A55 (Hudson D2) Micro ATX AMD Motherboard + AMD A4-3400 Llano 2.7GHz Socket FM1 Dual Core Desktop APU (CPU + GPU) + 8GB (2x4G G.Skill Ares Series DDR3 1600 Desktop Memory for $105 - $6 off promo code AMDFASTPITCH - $10 MSI rebate = $89 with free shipping.
Newegg Link:
Newegg.com - Computer Parts, PC Components, Laptop Computers, LED LCD TV, Digital Cameras and more!