Where to buy 2" thick foam board insulation?

I'm in the middle of a project replacing the plywood floor in my aluminum bass boat and also need to change out the flotation foam beneath the floor that's waterlogged. I've read on iBoats forums that a good easy fix for changing out the foam (without getting the pour-in stuff that may require extra knowledge to mix, etc.) is to go with the pink foam board found in hardware stores. This stuff is also "closed cell" so shouldn't soak up water it may come into contact with on occasion.

However, the problem is that I need the stuff to be 2" thick which seems to be impossible to find in any of the stores I've checked (Home Depot, Lowes, Stein, etc.) - they only have either 1/2" or 3/4" thick. Sure, I realize that I could just layer up the thinner stuff, but I've got to cut it into sections and I would rather just be able to go through one series of the cuts I need, not double, triple, or more. I could otherwise try to layer first, then cut all at once but would probably end up with non-uniform cuts in either situation....just seems like I should be able to find the 2" thick stuff and get this over with. Also, buying multiple thin layers might cost a bit more anyway.

I know Owens Corning makes it 2" thick because I see it on their website. I've already called them and they referred me to a local store who doesn't stock insulation but they're checking on special ordering for me. I just decided to go ahead and throw a Hail Mary on here too at the same time.

Geez, didn't realize it would be this hard to get the stuff.