(clicky to zoom in)
I just got the annual silver proof set and the coins look absolutely stunning. While much, much more expensive than just getting the quarters in your change (nearly $10 a piece with shipping), they are orders of magnitude better looking. These aren't coins, they are tiny works of art.
Last year's set (Hot Springs NP, Yellowstone NP, Yosemite NP, Grand Canyon NP and Mount Hood NF) is still available from the Mint, $15 for a proof set in cupronickel, $40 for silver. This years set (Gettysburg NMP, Glacier NP, Olympic NP, Vicksburg NMP and Chickasaw NRA) is $15 and $42 for cupronickel and silver, respectively.
Some time in the middle of next year, the US Mint will release a 5 ounce silver version of this coin. It's about 3 inches across and, barring a crash in silver prices, will be quite expensive (the current Yosemite 5-oz uncirculated coin sells for $280), but only 27,000 are minted, so this will be a very collectible item.