Best to go to a dealer. Most (all?) will not ship due to several reasons. There's also a core charge (usually $1350) involved till you return your old one. GOOD LUCK!
I think there is a dealer in Georgia (maybe?) that does a lot of online sales and actually gives an excellent price on the battery itself close to $2.1k. But it is a couple hundred bucks to ship it to you, and then you have to pay to ship your old one back to them which will be similar. Best to go to a dealer in your area. Some will not sell it to you over the counter, only if you have the installation done by them. If you are wanting to do the install yourself, then maybe phone up a few dealers in your area and see how much and if they're willing to sell to you. Remember all the dealers are not owned by Toyota. They are independent shops out to make profit. Toyota gives them a recommended sale price, the dealers on an individual level set their own final prices and policies.
Ok, found the pricing and the stories to go with it. Internet price, best case is $2070 but apparently good luck getting that.