I am not sure what exactly you mean by converter, but sounds like all you need is a video card. But you are correct in saying that they cost around $100 minimum.
If you buy a good video card you need to make sure your TV and your video card both need to have same type of connector (e.g. S-Video out on Video card and S-Video in for TV). You might check out this one -
http://shop1.outpost.com/product/398...H:MAIN_RSLT_PG