Looking to go tubeless wtb i25 rims so looking at 30mm tape. Can I find any for a reasonable price?

Any issues with buying 25mm and running two wraps to fill the width of the rim bed/well?

I use 2 wraps of 19mm electric tape, works fine.

Two layers of gorilla should do the job (50mm width roll and tear it down the middle)

It only has to cover the spoke holes

Well, usually. If these are the cheaper STs they might not have a perfectly airtight join in the rim. If it’s a Frequency or KOM that’s definitely OK though. With wide, quality rims I generally tape only the middle now- not where the tyre sits. The rims I use are airtight, and doing it this way removes any risk of damaging the tape while changing a tyre (since sometimes, the tyre will pull the tape off as it goes)