There are three great ways to get top quality performance for low prices:
1) internet-direct brands.
By cutting out the "middle man", companies that manufacture their own products and sell them directly to customers on the internet are able to offer higher levels of quality for lower prices.
Some of the most well-respected internet companies include: Axiom Audio, Aperion Audio, Ascend Acoustics, EMP Tech (a division of RBH), Emotiva, SVSound, Epik Subwoofers, Elemental Designs (eD), HSU Research, Salk Sound, The Speaker Company (tSc), Outlaw Audio, Blue Jeans Cables, Monoprice.com, Tartan Cables, Auralex, GIK Acoustics, RealTraps, Ready Acoustics...and I'm sure there are a few that I've missed
2) Buying used.
Sites like Audiogon and the classifieds sections of Audioholics and AVS Forums give you the chance to buy great, used gear. If you really know what you want, places like ebay and Amazon Marketplace can also be good places to search for deals on used gear.
3) "Pro Audio" gear.
Professional audio gear is often overlooked by consumers. But in terms of performance for dollars, it is hard to beat pro audio gear. Typically, because pro audio gear is not found in "consumer" retail stores, most people do not know about these products. Furthermore, the focus is definitely on performance and NOT on looks. A lot of pro gear is very plain and utilitarian looking. You might also find things like fairly large fans or lighted gauges that are useful for a professional, but might be undesirable in a "fashionable" home setup.
If you are looking for excellent performance for low prices, definitely check out Behringer pro audio equipment. JBL Pro also makes some nice equipment as does Yamaha Professional.
Right off the top of my head, if you are looking for excellent sound quality, you are not too picky about looks, and you want to keep the price low, here is one recommendation:
Behringer B2030P speakers
SVSound PB12-NSD subwoofer - decoupled with an Auralex GRAMMA isolation riser.
Onkyo TX-SR707 receiver (I prefer this slightly more expensive model - vs. the 607 or 507 - because it offers pre-outs so that you can add a separate amplifier or use self-powered speakers in the future if you want to).
Connect everything with speaker wire from monoprice.com or bluejeanscable.com and get your interconnects from monoprice.com, bluejeanscable.com or tartancable.com
I've given you a lot to research and consider. And I'm sure that others will weigh in as well. But that should at least give you a start
Best of luck!