The first thing to do there is edit your first link since that is for the intended speakers not any sound card. You posted the same link twice. If you are looking at speaker sets in the $45-$50 range, one set of Logitech X-530s open box however could work.
http://www.newegg.com/Product/Produc...2E16836121126R
Other 2 1/2 sets are seeing lower prices at
http://www.newegg.com/Product/Produc...08149&name=2.1
The Panasonic speakers off of a portable stereo or boon box may work since those are not being powered by the system itself. But what to use as an amp for them? you wouldn't hear anything by simply plugging them directly into the sound card since those don't include amplifiers.