When an artist signs an exclusive deal to release a CD or DVD with a retail chain, it can be good for fans because the price is usually very cheap. But it can also be bad when the retailer orders too much and can't move the excess stock.
For example: I was in WalMart a couple weeks ago and saw a few dozen copies of The Eagles' double album 'Long Road Out of Eden' marked down to $5. What a steal! If memory serves correct, the original price was around $11 - a real bargain for all that music. They shouldn't be taking up valuable shelf space in the ever-shrinking electronics section though.
Sam's Club, owned by WalMart, also had tons of AC/DC's 'Black Ice' on shelves for $5.
Then I went to Target's music department and a several dozen copies of Pearl Jam's solid 2009 CD 'Backspacer' were crammed into the 'P' section. Only it wasn't marked down. At least WalMart was smarter than its rival in pricing to move.
All of these releases are good (Eagles, AC/DC) to great (Pearl Jam), so if you've been on the fence about buying them, now is the time!