Get a small 25x2 amp, with two 6.5 or 6x9 speakers, and use a stereo to RCA plug to go into the amp. then use the mp3 player to change songs. very ghettorigged, but it will work just fine, and a small amp like that shouldnt cost more than 50 bucks, wiring, maybe another 20. speakers, a bit more.
simple.

89 4Runner
3" BL, M/T locks, 33"bfg mt, bilstein, Kayline, tubebumper, toyotafiberglass panels
TBI: Elocker,3.4 w/ORS,b+b,S2Sstg2cams,arias pistons,P+P intake,TRDs/c,URDpullies+7th,downey headers,MAPECU2,WEGO WB, SupraMAF,walboro255,stg4clutch, EPaOo2 sim