Last year I purchased WS fluid for $9.50 per quart. I went back to the dealership yesterday and the price is now $20 with no room to budge. Has the formula changed? I don't understand how the price has gotten to the point where I'd rather just buy Amsoil if I'm paying that much money.

I think that some dealers such as the one you stopped at are just raising the price, here's still some good prices out there even at some dealers.

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World Standard Automatic Transmission Fluid

Genuine Toyota WS ATF World Standard Automatic Transmission Fluid 1qt 00289-ATFWS-01 | Elmhurst Toyota Parts

Toyota Automatic Transmission Fluid ATF WS. Speed Industry | Aftermarket Performance Parts Store

If this place is close enough to you, just order it online and go pick it up. I've tried but they won't deliver it, but I like this dealerships online prices a lot.
World Standard Automatic Transmission Fluid

They still have good price.

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