If you can wait, save up more money and buy a better quality bike from a real bike shop. With such a long inseam for your overall height, you'd really be most comfortable on a bike made specifically for women. WSD bikes have shorter top tubes and longer seat posts to accommodate the differences in our anatomy over the typical man's body.
As far as size goes, you'd probably need a 54 cm frame, and as el guapo suggested, you can always go to a bike shop, find a bike that fits you, and then try to order something with similar geometry, but I'd hold out and save some more money if you don't have to have a new bike immediately.
Oh, and always check Craigslist too. I see some amazing deals on there, especially when people buy really expensive bikes then never ride them and try to sell them for half the original cost.
