The Blu-Ray version of the entire series is on sale on Amazon for only $14.99 with free shipping for Amazon Prime members or orders over $49.
The same deal is available via Best Buy, also for $14.99 and free store pick-up.
(via Slickdeals)
UPDATE 04/16/2016: The page on Amazon displays that the price is back to $28.99, but if you scroll down to look at other offers, you can still choose to order the $14.99 copy, even if it is temporarily out of stock.