well... theres a compromise being made then... ...the more speakers you have, the more its going to cost, especially if theyre good speakers... ...going less expensive however... ...either means purchasing less speakers (so you can maintain quality per speaker), or worse quality for each speaker, so you can afford more of them then
it really depends on what your budget is, for the most part... budget, room space available for speakers, intended use, etc
Edit:
really though, for <$100, if you want decent 5.1 or 7.1 computer speakers, your best bet is ebay possibly
for $100-200, you could probably find a decent pair of 5.1 unopened computer speakers, or maybe same or lower quality 7.1 computer speakers
for $200-300, if you have the room available (and a spare surround HT receiver), you can surpass computer speaker quality speakers, and jump up to HT theatre sound quality
beyond there though, you have any choice of speakers you want pretty much
heres a link to someone asking the same question, quite a few suggestions came up:
http://forumz.tomshardware.com/hardware/Help-choose-speakers-ftopict205840.html
IMO: computer speakers above $200 are simply overpriced for what you get, so, either way