Lifting at home is definitely advantageous for some. I did for a while, and it was the best for me at the time. Now I have a gym across from work and mostly use that. My next step will be to get a Concept 2 rower for home. I want a machine so I can warm up easier. I don't enjoy running, air squats, etc. as a warm up… I'd rather just get on a rower for 10 minutes.
If you want to save money, craigslist is the place to look for weights. Iron doesn't change with time, you'll save over 50% compared to new. Used - expect to pay about 50 cents per pound of iron weights, and most areas should have plenty available. I have 300# Olympic set, and I think 600# in standard 1" weights which I mainly use for dumbbell work. I ended up buying a bunch of dumbbell bars from Walmart so I don't have to change them as often. Adjustable dumbbells will be much more than 50 cents a pound.
You can also find a power rack and a bench on Craigslist, but you may have to be more patient. I didn't want to be, so I got a new power rack from NY Barbell which I'm quite happy with. It is about the same price as the amazon one, depending on shipping. I'm happy with it and other equipment I got from them:
http://www.newyorkbarbells.com/92563.html
I found a Body Solid incline bench at Play It Again Sports. If I were to do it again, I would not get a flat bench, not incline. The rarely use the incline feature, and the bench shifts slightly under weight. I think I paid like $60 for it, but it is $300 new on Amazon. Not recommended.