This is quite a bit more expensive than agencies I've worked with in the past, and those typically involve a translator + proofreader who are at least somewhat

This is quite a bit more expensive than agencies I've worked with in the past, and those typically involve a translator + proofreader who are at least somewhat knowledgeable about the topic being translated, so the quality is pretty good. I suppose some people will be happy to pay a premium for a quick turn around, but personally I care about the quality much more than the delivery time.