You probably already know the "Big 2" are Meade and Celestron

. Given how much the pricing has dropped in the last few years I wouldn't consider not getting a computer controlled scope - it saves all the agony of learning celestial navigation and does the tracking for you so whatever you are looking at stays in view. Not finding what you want to look at has to be the #1 reason people give up on amateur astronomy, so make it easy on yourself. Besides, the resale value will be better if you do decide to move on to a different hobby. Yes, bigger is better for aperture, but also consider a refractor vs. reflector. Do you want sharp images of the planets or maximum light gathering? It's a little over your price limit but Celestron has recently come out with a 5" Maksutov-Cassegrain, the Nextstar 127 SLT, computer controlled with two eyepieces, and 3-4 vendors are selling it on ebay for under $480 shipped. I really, really want one for Christmas

. Small enough to be easily portable (will go in a suitcase), good light gathering power, good optics, computer controlled - dang it, I'm talking myself into it

. Seriously, both Celestron and Meady have 5" Schmidt-Cass scopes but they are $100-200 more than this one, and this one is a decent step up over the under $300 models. Go to
Meade Instruments - Telescopes, Solar Telescopes, Telescope Accessories, Telescopes by Meade and
Celestron Telescopes, Telescope Accessories, Telescopes by Celestron and browse, then go to ebay and price shop. There are other brands but I'd stick with these two at first, until you better understand what the tradeoffs might be.