I think what you should do is sit back, digest all the information you have already been given, some of which includes suggestions on bikes that may fall within your price range as possible second-hand bikes. Have a look at ebay and pinkbike once you've decided which bike you would like to get your hands on. If you find a bike on either copy and paste a link, and I'm sure we will be happy to help.
Ask yourself if you want a fixerupper and if you have to knowhow to fix it up, or do you want a bike that is ready to ride. Once you have a firm idea in your head about what it is you are looking for, then you will start making informed choices.