Good question. It depends on the publisher. I usually look up both. If Amazon is significantly cheaper (tens of dollars), then I'll order from Amazon. If they send me garbage, I'll order from the publisher and return the Amazon book.

I may be in a niche circumstance, but most of the books I order from the publishers are within about $5 of Amazon. I don't know the exact count, but I have approximately 600 books. Worth it to have nice ones!