As of this week, WWE WrestleMania I-XV are now exclusively available as single disc DVDs at Walmart. The DVDs are also on sale on online retailers like Amazon.com, so the exclusivity is likely for physical in-store purchases.
The WrestleManias were previously available as part of WWE's anthology set, released in four volumes in 2005. Amazon also has listed re-releases for WrestleMania 23 and 25, which are set to come out on March 26.
There have been several edits made to the I-XV DVDs, which you can read about here. WWE previously had to blur and cut footage due to the ongoing agreement with the World Wildlife Fund.