A tooth of Dahlver-Nar (associated with Savnok) will let you ignore any movement penalty due to armor. It is a slotless magic item and costs 2000 GP (ToM pg. 77-79). The caveat is that you are always under the influence of Savnok (ToM pg. 45-47), so yo cannot ever undone your armor or drop a shield (if you pick one).
Addendum if you coonsider using the tooth you might want to look at the Restful enhancement from Dungeonscape pg. 39.