> I thought Visa had a hard limit of $2k USD per day.

Of course not. Maybe your bank has such a limit on your card, but there's definitely no hard limit that low imposed by any of the Visa/Mastercard/Amex. How else would you buy things over $2k?

> And $10k limit for ACH? You can transfer more money than that via SWIFT.

Not surprising. It seems ACH is still run with punch card technology

Limits vary based on your bank, card type (debit vs credit), account type (personal vs. business) and what you're doing with the money (withdrawing cash vs. spending online). You can also ask to increase the limit. People can also get multiple cards and use them for online payments.

  ... limit of $2k USD per day.

AWS and AdWords both accept cards and people spend a lot of money there. Online accommodation booking can cost more than $2k and people have no problems doing it.

If you have items with high prices, just send users a quick notification to check whether their cards have a limit and to ask their bank to lift it.