Hi Kelly, I'm almost exactly your size too. I was also a runner turned cyclist (and now cycling is my MOST favorite thing to do!)

Totally agree you should go around and ride as many bikes are you can. You might take along a little notebook and take notes. Size of bike, exact model, if they changed the stem before you test road and what size they changed to, what you thought of it etc. After you get home you can get online and print out the geometry chart off the internet for the bikes you rode. That way you can start to get a feel for what top tube length is most comfortable etc. You can check out this too to get your own ideas about fit. http://www.competitivecyclist.com/za...LCULATOR_INTRO

I am also a very competitive and warn you that if you buy a new bike for less than $1k you are going to probably end up with something with parts that don't work as well as you're going to want them to. Example, Shimano Tiagra or Sora parts called "components". These lower end parts don't work as smoothly and shift as effortlessly (especially when you're riding hard!) as you'll want if you're interested in being competitive. So test ride things that are higher end, for more like $1500 you can get an aluminum bike with a few carbon parts as well as Shimano 105 components (thats pretty much the midlevel parts that start to work well). From there if you jump to $2000 you get the same 105 components just with the entry level carbon frame. As a beginner I wouldn't recommend that you need to go that high. Apart from price range the most important issue you're going to face is the "triple or compact" question. That means how many gears up front between the pedals (aka crankset). Since you're already a runner I would recommend you go straight to a compact. That means you'll still have access to lower gears to make hills easier BUT you won't be stuck w/ a triple with makes shifting a little slower, puts your feet a little too far apart (maybe)....oh and also noone races triples....Changing a bike w/ a triple into a compact is way more complicated that you would originally think and involves changing multiple parts so its best if you can just get what you want from the beginning.

Ok, regarding Ebay, it is your best best (IMHO) for getting a good bike in a price range you can afford. If you drilll down (categories - sporting goods - cycling - complete bikes - road bikes) you can get better results than just searching "road bike" etc. You can even arrange results by size, material, etc. Also, I don't know if your price range included all the extras you'll need. Don't forget that you'll need at minimum a helmet, a pair of cycling shorts (with chamois) (and maybe tights too since its cooold), and cycling shoes. Most people choose to use clipless pedals (special shoe w/ a bit that attaches directly to a special pedal to allow you to pedal UP and sideways as well as just push the pedal down) but you could always start with a simple cage system that you could use your running shoes with. You can always go to the gear section of Team Estrogen and ask for people to sell you used stuff in your size. These women are ammmazing like that!

WOW. I had a lot to say. I was exactly in your shoes 6 months ago so I feel great empathy! Best of luck!!!