well you have a few options available to you.
you could connect both up to the television and use the televisions audio out to go to the soundbar
you could have a seperate wire going from each source to the soundbar and use a splitter (but you could only have one device set to output sound at once this way)
a hometheatre in a box solution might accept two inputs and act as a cheap receiver/speaker combination, however the speakers you will get are typically little junky plastic ones so i find this hard to recommend.
you could link both through a cheap receiver and get a few speakers to hook up. this way might blow your budget by a little bit.
personally i have my ps3 and pc hooked up via a receiver and that connected to a 5.1 surround system and 40" tv. i spent quite a bit more than $200 (i had a bigger budget) but overall i'd say its worth it.