http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=200645841027+ $129 free shipping--- I seem to remember these being more pricey.
Mintproducts.com has them for $119.95 and you will not have to worry about quality or whether or not they are silver. TC
They were selling for more than that in 2001. Not so long ago they were $400 and up. I sold one to a forum member for $250 when the going rate was over $300 so she could give it to her husband as a b-day present. She was ecstatic as was her husband when he got it. The price history is pretty typical of most mint products in one regard - those that go up soon after release eventually fall to near issue prices. 'Course most people don't want to hear that because they pay outrageous prices for current, or recent, mint products. Well, get ready for it. But watch closely because they don't make any where near as much noise when they fall into the basement as they did when they shot into the attic
The "relative" mintages and popularity of the State Quarters shot these into the stratosphere! The mintages haven't changed but the popularity has dropped to almost zero as these are no longer "THE" thing to collect. Out of sight, out of mind, and back into an affordable price range!
The reason lower prices are down played is: People don't want to set off alarm bells and alert others, while they are trying to sell and get the best price. And those that choose not to, don't want additional panic sellers lowering prices, further yet. It's human nature.
The silver proof's will always perhaps demand a little more than their clad counterparts. I use to collect the clad's back in the day, I still have them but I don't opt to buy them nowadays. I'll pickup the silver proof sets (since they're not clad) and the uncirculated sets (which seem to hold onto their value or go up over the clad proof sets). Honestly, I'd say wait another couple of years to pick up the silver proof sets you don't have, they'll likely continue to lose demand and drop more in price. I have a few I'm missing as well, I'm waiting as I don't want to spend over $100 for the 1999 or the other early 2000 sets.
I bought my 1999 set from the Mint in 99. I believe it was in the Mid $30 range. When it jumped up to $400. I started buying two every year. No other set has jumped in price like that, but all of my double sets have done well since silver has climbed in price. The 99 price jump paid off in more ways than one.
I bet that most of the sets on eBay have been cherry picked. If i was buying a set on eBay my bid would be assuming that the guys had made up that set from leftover coins that did not grade well.