Amazon has Iron Man 2 {Blu-Ray} on pre-order right now for only $17.99. It will be released tomorrow (9/28) so this should be the lowest it will go. If the price of the DVD does go lower before tomorrow, you will pay the lowest price! You can also get the DVD for only $16.99. Both ship free with a $25 purchase, Amazon Mom or Amazon Prime.
(Thanks “Cents”able Momma!)