Best Place To Purchase 90% Silver Rolls.

OK - I see the prices of circulated or BU rolls of 1964 and older dimes, quarters, half dollars, etc. on places like ebay, dealer sights, etc.. For those of you that purchase such items, do you find that ebay and most dealer pricing to be on the high side, or are these prices about the norm? I'd like to purchase rolls of the above and could purchase some quantity if I desired. Should I be looking to buy at shows or somewhere other than ebay or most dealers? I feel like I'm really missing something here. If folks on ebay are selling at such prices, they have to be purchasing those items cheaper somewhere. Sorry if this sounds like a really dumb question, but I've been stumped on this subject for a while now. As one example, I see rolls of BU 90% Roosevelt dimes selling for anywhere from $70.00 to $120.00. What type of price is considered the RIGHT price for such an item. I need some expert guidelines. Your replies are much appreciated, as are any suggestions on the best place to make such purchases!

Dom in Jersey