Good advise from CU and Powder. I also advise getting the biggest and heaviest you can. Mine weighs 3,000 lbs and many times I wish it were bigger. I know that right now you are thinking about just making models, but once you have a lathe you will wonder how you ever survived without one and you will discover how many times you will use it for many other things. Like the time I discovered an aluminum wheel on my truck wasn't running true, hey no problem, I can fix that.
Trying to find a good old lathe will be the hard part though. Very many of the old lathes will be worn out so I just advise doing what you gotta do to get one. I would highly recommend finding a machinist to help in your search as it is very difficult for a novice to even know what to look for when inspecting a lathe. A very good way to go is to buy what you can find at a good price and keep up the search for a better one. This way you do have something to use until a good one comes along.
Getting a machine from ebay can be a great deal providing you can inspect it before you buy it. But the most important thing is, without experience you need help from somebody to make your choice.
Sorry, didn't mean to write so much.
Michael