Well as we all know, Buying hard copies of games from local stores is all but gone(although I did see "Gray Matter" offered at Wall Mart for 20 bucks!)
You can still get them from Ebay or Amazon etc. and this works well! (Just bought "Immortals of Terra" on Ebay for $1.45 plus shipping!!!!)
But Downloading seems to be the future. As we all know in the world of computers there is constant change! These are my favorite sites to download from, The prices are good, they always run specials, and they are usually in a more up to date format and seem to run better on more contemporary systems. Some of my older discs wont run on my newer setup (3+ years old).
The adventureshop link on top of forumhttp://www.gog.com/en/frontpage/http://www.gamersgate.com/http://www.dotemu.com/en
Also Steam is a good site, its a pain to get set up, and you have to be hooked up on the internet to play the game, but their selection is enormous and prices and ancillary services good!