A few weeks ago I went to a SM and bought GC's for the first time, just bought $500x4. The lady at the kiosk was pretty clueless about the cards; for example she was pretty sure they weren't PIN-friendly, which of course wasn't true.
I had a weird sort of "YMMV" experience trying to unload them. I went to an unfamiliar WM and was told I couldn't do it without an ID that showed my name was "Especially For You" - the "name" on the card. So I took them to my "home" WM where I'm on a first-name basis with the Money Center staff.
So this week I called a different SM. They were extremely nice and had my order of $500x18 ready for me when I got there. I met the manager, who encouraged me to submit the corporate form for pre-approval. Neither of these malls are that close to me, but they aren't all that far out of my way sometimes.
One thing was inconsistent with what I've seen on this forum; the corporate cards still have a $500 max, although the price is $2.50 if you buy 25 or more. If they want to sell me $500x25 at a time, I'm all good with that, and anyway the credit limit on the card I use is only $15K anyway, but is it possible that the max per card on a corporate account is $1K and there's a way I can prove it to them? The form says "Maximum Value Load $500."