Oh, and the guy at the store’s opinion: “you can’t go wrong with a Strat.”

I disagree. Strats are too heavy for my liking and haven't evolved much beyond their origins. Their history is too steeped to allow change.

But that is a personal preference.

One thing to consider is that many humbuckers have a center tap which allows them to be used in a single coil mode, meaning that you can have your cake and eat it too.
The intended purpose of a humbucker is to increase the signal to noise ratio - effectively they can double the signal from the strings whilst eliminating pickup of background electomagnetic noise. While you may prefer the single coil sound, you may find that on occasion the humbucker is useful. A center-tapped humbucker would give you this flexibility. Another option would be to find a guitar that has both single and humbucking pickups installed.

Don't forget to check out other manufacuturers too. eg, Ibanez. The S470 falls into your price range, has 3 pickups in a HSH configuration, a lightweight mahogany body, rosewood fingerboard on a maple neck yada yada...

[edit]
I see that Tony and Bitt got in here between me writing most of this post and actually submitting it. Oh well.