Buy something that fits from a local shop that treats you nicely and appears to be willing to take the time to make it fit right. For that price you can get a bike capabile of winning the olympics, I have no idea what you need, you'd need to explain why you want a bike and what you plan to do. Are you looking for a tri bike or a road bike? They are different.

You might be best served with a standard road bike, a Tri or "TT" type bike is designed to be ridden in the aero bars mostly and can be a little specialized and uncomfortable.

If you have normal fitness and don't live in a super hilly area, you may wish to avoid the triple cranks that come on many bikes in the lower price range, instead ask for a compact type cranks set. At your weight, the weak point on mid range and lower bikes will be the wheels, you may wish to switch them out for something more robust. I have been training on teh Roval wheels this year and beat the snot out of them, they are a great wheel.

If the shop won't swap out parts to get the bike how you want, go elsewhere. I'm buying a bike this week and the shop said anything I want to swap is fair game, it may cost extra or not and I may bring a few used parts in to put on, but it's my bike and they make it how I want. A shop gives yo any lip about that, go find another one.

Once you get a few candidate bikes, post them here and we can take a look. Any bike in your price range will be decent, brands are not important.