Shane, I found one at Amazon.com - make sure it's from Amazon and not another seller (i.e. Office Depot ships via Amazon, but charges A LOT for shipping). Add something cheap to get over $25 and shipping is free.
Here's the battery for $24.99 http://www.amazon.com/exec/obidos/AS...525527-9120109
Keep checking back, it comes and goes.
I ordered batteries for $1.50 to get over $25
I just got my DX6490 last night, and am having a blast!