Presidential Dollar Severed Head/Starburst Errors

I picked up some George Washington dollars this past week and looked through them for a)my dansco and b)errors. I found some 'severed head' as well as some starburst errors (I know, you all want to see pictures, I'll work on that for you). Following the find, I did some light research on ebay and only found a few severed heads, which seemed to be in the $5-9 range, and quite a few starburst, which seemed to be in the $1-4 range. I want to know if you guys think this sounds right. Do you see any premium on these in the future? If you find a lot, do you keep them (this applies to all presidential errors, and I guess errors in general)? I want to, but then I ask myself what I'm going to do with all these error dollars sitting around that most likely won't go up much in value. I may keep one for myself and use the others as trading material once I hit the coveted 50 post mark.