Usually, where BTC is also accepted, it doesn't cost more there to use BTC. Usually, Bitcoin backed credit cards have terribly high fees, so you claim to pay with Bitcoin but the merchant is not a bitcoiner and couldn't care less about bitcoin. I think, companies that accept Bitcoin directly deserve our support and I'm willing to pay some 2-3% for the pleasure of supporting the Bitcoin circular economy but not 10% unless it has other things going for it. So I ordered at least 20 times from Fasttech. Sadly they are no more and I wish there was some comparable platform where I could buy all that stuff I'm currently getting from Amazon.