If u want any decent sound at all, they'll prolly need their own power supply. And changing batteries in your speakers sounds like a pain in the ass.
If you don't want a sub, just go to newegg and look at 2.0 speakers, and read some reviews.
FWIW I have Klipsch 2.1 speakers and while they were probably a little overpriced, they've run fine for ~10 years.
When I was in highschool, I got a pair of 3 ft tall speakers. One day for no damn reason my neutered cat sprayed all over the mesh on one of them. ****er!