Watch out if they are el-cheapos since there is a brand or two from China for less than $10.00 on a lot of sites, some even with free shipping.
I bought a DiMarzio
250K P/P switch - the same as you are looking for, and it is about $12.95 across the boards for availability.
Check out DiMarzio's site itself and see all the great stuff they have for sale:: DiMarzio.com
Just like this one HERE: Buy DiMarzio 250K Custom Taper Split Shaft Push/Pull Pot | Potentiometers & Knobs | Musician's Friend
Beware that there are three different shaft lengths too - and some of the other pots from Stew Mac
have smaller soldering tabs than the DiMarzio. I suspect these are Chinese too.
There are other places that say they sell DiMarzios for $13.00 or so, and that seems to be the best prices for a good, rugged P/P pot. AllParts
has one for $6.00::: Allparts EP-0285-000 250K Guitar Push/Pull Pot DPDT Audio Taper Pot
I'd worry about that one though.