The difference is in the tech. Each tech has it's up and downs. DLP's have nice picture quality, the problem with those in my opinion is that they are bulky and can't be viewed very well from angles. Plasmas have great color and picture quality, but from I've heard they suffer from picture burn-in. So if you're a gamer, don't get a plasma. If you're not it'll suit you fine. They are flat too! So you can mount them on walls and save some space. I haven't heard much complaints from LCD's. They appear to have a more washed out color than the other 2 types though. That's not to say they look bad, its just that the colors look a bit more vibrant on the other types. They don't seem to suffer from burn-in, so I recommend this type if you're a gamer.
Anyway, I was at BestBuy the other night and I saw a 52in Samsung LCD 1080p for around 3-4k. Sounds like a very good deal to me!