Hello Primus6, welcome to the forums
The general lenses that you get off of ebay, which appear to be great quality, are not matched properly for use with the S2 and S3. They give very poor images. Most would argue that the S2/S3 can not handle anything more then a 1.7x ish tele adapter (which is still ALOT). Wide on the other hand it not 'as' big of a problem. Most still produce good images at full wide, but crap when using alot of zoom. I got mine off ebay because it was a cheap set. I knew the 3x tele was abit much, but the wide/fisheye is amazing. Its a big risk finding something that will work.
Chack lensmateonline.com for sample pictures taken with the S2/S3 with some very good lenses. Dont get them off ebay, go with Canon, Sony, Raynox etc... and always see sample pics from the same camera and lens combo. Anything else and there is no garuntee it will work.