Centurion Signet Road Bike, worth $200?
 

I don't know anything about bikes. I'm petite and looking for a good value bike on a budget to commute to work. Is this worth it? Would love your help. There's not much info on it except that it has newer tires.

http://sfbay.craigslist.org/sby/bik/4218538582.html

I believe the Signet is a very low end model with a hi-ten steel frame and steel rims. At $200, I think it's priced too high even for the bay area market. OTOH, if it is your size and in good shape, it may be worth it to you. Finding such small frames is difficult, and even at $200 it's more bike than you'd find for twice the price at Wal-Mart.

I'd try to negotiate a lower price, say $100 - $125.

EDIT - Bill beat me to it. :D

I agree with thrifty bill that the bike is overpriced but it is going to be hard to find a road bike that small. Probably your best bet for a small frame is to go with a vintage mountain bike. The 26 inch wheels are a big plus in a smaller frame and vintage MTBs tend to be more reasonably priced than equivalent era and quality road bikes. Plus they have nice fat tires for commuting. Just make sure you get a bike with a rigid (not suspension) fork; there's less to go wrong mechanically and a rigid fork is better for road commuting. Something like this diamond back at $125 might do the trick: http://sfbay.craigslist.org/sby/bik/4247416862.html.

Lot's of cheap mixtes in SF Bay
A steal Mercier Mixte
http://sfbay.craigslist.org/eby/bik/4263853586.html

Small Jamis
http://sfbay.craigslist.org/pen/bik/4249545151.html

Gitane Mixte
http://sfbay.craigslist.org/sby/bik/4235456313.html

Puch Mixte
http://sfbay.craigslist.org/sby/bik/4258627222.html

Univega Mixte - bad pics, good bike
http://sfbay.craigslist.org/sfc/bik/4247721932.html