Sounds like a plan. Now you just gotta do it. Niche is a great way to go if you're going to start a tgp.
You should definately check out
Jmb Soft for a TGP script. Autogallery SQL has a ton of features and it's only $85.00. Autogallery Pro is cheaper and lacks some features, but probably still great software. It'll be a breeze to integrate your current design into it.
Check out Arrow Trader Lite 3 for a trade script. Great combination there.
Once you get it up and running, use
Choker Traffic for some feeder traffic to get your trades going.