You looked online where?
Call your local Yamaha dealer. Pretty much all the engine seals are available new. That being said, the MikesXS kit contains the same seals for 1/2 the price, if you're buying the whole set. I had the MikesXS kit, and was convinced that buying OEM seals was a better route.
So I did that, spending $80 on a set of new seals from Yamaha. Turns out they're identical to the ones in the kit from MikesXS, down to the branding on the seals etc. No matter as I have another engine to build.
Invest in the kit as you'll have to replace your clutch rod seal, shifter seal etc. eventually.