$75 is pretty low. If you can get the promedias for that little then go for it, everyone I have talked to who has heard them likes them.
If you can't find them for that then get a pair of Realistic Minimus 77 from ebay for nearly nothing ($20 shipped). And grab an old SANSUI reciever from ebay as well for almost nothing ($50 shipped).
I have done this a few times now for different garage systems and whatnot. Sometimes you can get a really good deal. Almost all of the Sansui stuff (especially if it has wood on it) is pretty decent, and the Realistics (although leaving something to be desired) are also quite good for the money. This also lets you get better speakers if you want, use the headphone amp in the Sansui, which is better than your computer's, and upgrade the receiver when you want. It's also standalone, so if you get a better computer rig, it can still run Kitchen/Garage/Basement duty.