Personally, I wouldn't trust a speaker that did not publish true frequency response and/or offer graphs. I don't think that I would trust a speaker that I couldn't hear first either.
Despite that, you could use a set up like the Logitech 2.1s recommended to you previously (there is also a cheap Tascam 2.1 set up that I have seen recommended before), but recognize that these are not monitors and they are not accurate. Now, that doesn't mean that you can not use them to mix with but you will have to learn them and don't expect things to translate to other systems well. Also, THX multimedia is not anything like PM3 certification for a studio.
Finally, a great company (which happen to be the monitors that I use) provide anyone and everyone with very good calibration and set up recommendations for 2.1 systems. The name of the company is Blue Sky and they also offer bandwidth limited test files. Just look around here:
http://www.abluesky.com