Has anybody ever purchased a miner directly from bitmain? I noticed that they (as well as most/all other miner vendors/resellers) all seem to only accept payment in crypto or in one case a wire transfer. How can I be sure that they actually send me the hardware after I pay? And what about issues with import complications?
Bitmain has the largest market share so yes you're going to receive your miner. I've ordered with them before. They will charge a premium on whatever miner you want to buy and charge the full import cost. You're better off going with a third party re-seller since they're more likely to give you a better price.
All vendors accept crypto because it's the easiest to use for large purchases, less friction with banks, less oversight, quicker simpler purchases for everyone involved.