if you plan to connect television and perhaps a few other perepherals you would be best suited by a receiver.
the numbers reflect the audio setup being used.
2.0 = two speakers, stereo sound.
2.1 = two speakers and subwoofer, stereo sound
5.1 = five speakers and subwoofer, surround sound
5.2 = five speakers and two subwoofers, surround sound
etcetera.
for music anything more than 2.0 or 2.1 isn't needed.
to get surround sound in movies 5.1 is what you want.
prices go from high to low: floorstanding, bookshelf, satelite speakers.
there are solutions for every kind of budget. you might want to state a roundabout figure that you were thinking of.
if on a budget:
onkyo receiver $50-100
sony tower speakers $100-200
$cables and clips $50
in total that is around $200-350 depending on multiple factors.
for a cheap system with a subwoofer add another hundred at minimum.
we bought some floorstanding speakers from sony awhile back at around $120 and two came in a box. they have multiple drivers and can produce bass low enough to not require a subwoofer. not the best speakers in the world but definitely a good value for the money spent.
for reference... a mid level system which i own:
$500 pioneer vsx-30 receiver
$550 klipsch quintet iv 5.0 satelite speakers
$350 klipsch 450w subwoofer
$100 two spools of cable, bananna clips, wall plates
in total around $1500 or so for a nice set of satelite speakers.
if you want another option between the two:
$200 pioneer receiver (lower end)
$170x2 klipsch tower speakers (lower end)
$100 cables and other accessories
in total about $640 for a middle of the road 2.0 system. at this level add $150 or $200 minimum for a subwoofer.
remember.... these are just examples of what you could do. your budget and needs will reflect what you can actually do. you need to think about things and post what it is that you want and what you can actually spend. keep in mind to note things you may need such as cables, wire ends, wallplates, cable organizers, etcetera.