I know its not what you want to hear but I would never buy a bike from the big chain stores. They sale bikes in 1 size (pretty sure it will be to small for you), offer no support and pretty much sale junk.
That being said it will cost you about 3 times that to get into a basic low end road bike. Fit is the most important aspect when shopping for a bike. If you are not comfortable on the bike you will not ride it. A good bike shop can take some basic measurements to get a ball park size. However depending on the bike you may need to go up or down a size (they all measure their frames differently). As a beginner I would not worry to much about weight (although 30 is pretty high). Gearing can be a big thing if you live near and ride hills.
A few examples...
Felt F95
Fuji 1.0
Scattante R33
There are a ton of road bikes in this price range.
Also if you know what size you ride and what your looking for you can get a lot more bike for your money buying used. My first 3 bikes were used and I put lots of happy miles on them.
Also bike shops have a bit of leway on there prices. They can bargain a bit from the sticker price or throw in some of the little things you will need to sweeten the deal (helmets, bottle cages, bottles...)
If you have any specific questions shoot them out here.