The closest we have to that is our Starter plan. If you factor in the two-week trial, you get 6 weeks to find market validation for your idea at a cost of only $14. It's a pretty reasonable expense.
We treat Bitpay transactions the same as any other in terms of fees/pricing. There's a 1% or 2% transaction fee on plans with lower monthly fees, but those are waived if you use Shopify Payments for credit card acceptance (even on Bitpay transactions).