I used a white Epi TB in a rock band for over a year. It was completely stock and completely fantastic, I loved it. I fully expected to have to upgrade the guts when I bought it, but I was wrong. It sounded immense straight out of the box, just a bit of a set up and it was ready to go. BIG thump from the stock pups no problem at all, great bass.
For your price range though, I personally would be looking for a second hand Precision, US or MIJ would fit the bill perfectly, and as a big fan of the Seymour Duncan Quarterpounder, I'd be thinking of dropping one of those into it for a [i]massive[/i] thumping tone.
Edit: or an Epiphone Jack Casady, that'd have a great tone for what you're after too I'd say, superb with flats.