I had a look at bookshelf speakers in your projected budget.
For your front left and right speakers, I would suggest the Klipsh Reference R15-M Bookshelf pair at $224 from Amazon as well. This is a good value and the customer reviews are very positive indeed.
As for the center speaker, I suggest the Klipsh R-25C unit which slightly exceeds your projected outlay, but this would also better match the other Klipsh speakers.
Note that if you choose to get the Klipsh set of speakers, the Denon AVR-X3300W receiver should be powerful enough because these speakers have a high sensitivity. If you don't need 9 amplifying channels, you would then save money on the receiver which could be used to put on these more expensive speakers.
For a subwoofer, I would rather suggest the Fluance DB12 Sub for $300 also, which will perform better and deeper than the Klipsh:
http://www.audioholics.com/subwoofer-reviews/fluance-db12
To tell you frankly, I wouldn't trust what a Geek Squad team mate is saying. Most of them don't know what they are talking about, and that goes for all large surface chain stores, not only BestBuy.