This is my creation. I put to pc speakers and their amp in bag. Its runs on two 9v batteries connected in parallel for longer work. Everything is made for 25 $. It has one 3mm jack, five w amp, two 9v battery, and two 6 watt 4 ohm speakers. I only need to put protective net over speakers.
I made this thing in 3 hours, lot of things inside are recycled, like battery clip and bag. (Bag was broken so i sewed it).
Sorry about my english, im from Croatia.