Speaker system suggestions

I have 2 soundcards, a c-media and a creative onboard (both are 5.1 comp).

I also have a cambridge soundworks speaker system ( the old ones - 2 tiny satellites and a sub) which is giving me trouble.

I paid around $17 (R200 in South Africa) and it costs me around R60 and a 2hour drive to get it replaced ( its still under warranty).

What other speaker system can I buy for around the same price but still retaining the same or better sound quality?
I am willing to pay a maximum of $45 ( R500)-don't laugh it's all i have -for a good speaker system
Or should I just get my current faulty one replaced?

Thanks