I don't frequent this forum much, but I've already noticed the amount of "What do I need?" threads. So I'll make this short and sweet...
First off, you need to consider how much money you are willing to spend. Let's face it, home gyms are not cheap, but they probably save you money in the long run. If money is an issue (which is almost always the case), be picky in selecting equipment. Search for the best deals on ebay, craigs list, and your local sports store.
Now, what do you NEED?
First and foremost you need weights. You can't lift without them. You can get a 300 lbs of olympic weights for $110 (including a barbell). If you pay more than that, you are getting ripped off. Places like Modells, The Sports Authority, and Dick's will run sales at this price. Now for me, 300 lbs was not quite enough. So I bought 2 more 45 lbs plates. It cost be $50! If I were to do it all over again, I would have just got 2 300 lbs sets. With a barbell and weights alone you can get a heck of a lot done.
The second piece of equipment I would get is a power rack. There are thousands of types on the net. I got mine for $370 INCLUDING shipping and handling. If you are ordering this on the net, be sure shipping and handling is included or else your looking at another $200.
Next, I'd probably go for an adjustable bench. You should get one that can be adjusted to incline, decline, flat, and at a 90 degree agle. You should be able to get a sturdy one for $90, if not cheaper.
Finally, I'd go to Walmart and get a pair of adjustable dumbbells for $20.
Anything else you get is just icing on the cake. If your really tight on cash, get creative. Build yourself some equipment if your handy.
So for the equipment listed your looking at $600 (if my math's correct). Gym pass, gas to and fro, its not that much more expensive. And its open 24 hours a day!
Hope this helps, feel free to add stuff...