I'm 5'0" with a 28 inch inseam, and am a new rider who first got on a bike at age 45, so I understand how frustrating it is to buy a new bike. I currently ride a 43cm Trek 1500 that I got on ebay for 1/3 of new retail price, and it's in nice shape--came with a trip computer that I would never have bothered to install, and it fits me well. I also bought a 42cmish 1987 Bridgestone 550 on ebay for about $350; it has the smaller front wheel. The Trek, like many of the smaller size WSD bikes, has 650 wheels which I find a lot easier to handle than my old bike, a 46 cm. Bianchi Brava whose bar I could barely clear. When I had a painful accident coming down on top of the top tube I realized that I needed at least an inch or two of standover height. My commuter is an old Panasonic mixte with big knobby tires, fenders, and North bars--that was an ebay find too. Mixtes are often small bikes, good for shorter riders because of the sloping top tube.

the smaller road bikes do show up on ebay sometimes, and I went that route because I live in a tiny town with only two bike stores that never has small sizes. I had to take a chance on sizing because of not being able to test ride ever, but I'm happy with the result. Only downside was that this process took several months to find, put together, and get these bikes the way that I wanted them. It cost me more in time than money. but it was fun.