I bought a pretty nice olympic barbell for about a 100bucks, and bought used weights at Play it Again Sports. Picked up a decent bench with spotter bars and uprights at Walmart. Worth every penny I paid. I've added adjustable dumbbells, a pullup bar, various grippers and miscellaneous equipment, and have recently bought my first KB.

My office has become my own personal gym, and I have everything I'll ever need without the hassle of a big, lame gym.