a few options...
you could go with some powered speakers like..
mackie cr3, cr4
m-audio av32, av42
micca pb42x
for a bit over budget there are products like the rokkit 5 and a2+
you could go with some passive speakers paired with an amp like..
pioneer bs22
klipsch r14m, kb-15
micca mb42
dayton b652 (quality has varied over the years, not sure if its in a good cycle or not right now)
amps...
the dayton dta-120 is excellent for a budget amplifier
for cheaper and low power you may be able to make do with a cheap lepai-2020a or similar
keep in mind that for low price you get low power amplifiers and things like the lepai really are low end and are only so good.
if you wanted a subwoofer to a 2.0 system you could add...
dayton sub650, sub1000
polk psw10
may bring you a bit over budget depending on your choices though but its relatively in the same area as you wanted.
if you wanted something more in the line of traditional pc speakers...
klipsch promedia 2.1 (good set but the subwoofer needs to be turned down as its a bit overpowering)
creative t40 2.0 (no subwoofer so lacks bass but has good audio quality)
jbl creature iii 2.1
harman kardon soundsticks iii 2.1
speaker sets from logitech and creative in general are decent quality. average for sure but good value.
edifier has some decent speaker options as well. 5.1 sets are available if you wanted from a few manufacturers
if you had more budget, you could get into something like a home theater system.
i personally use a home theater setup for pc from klipsch and it works great. i decided on it after using the promedia 2.1 which wasnt quite what i wanted but i was still impressed so looked into their speakers. before that i had used logitech for years.
as far as wattage, i'll let you check on that yourself.