$25 for a viz, per tank? Shown on receipt as "assembly", but he asked for, and presumably got, a VIP (i.e. including a new, current VIP sticker). That doesn't sound unreasonable to me, at all.
It seems like the only thing they might have done differently, MAYBE, is tell him "these are brand new and don't need a VIP" and saved him that money. But, since he brought them in with the valves off and they had to put them together (as trivial as that is), I can't see faulting them TOO much. Especially if he got a new, current shop's VIP sticker on each tank. And especially since maybe the only way they could be sure of saying "these don't need a VIP" is by ... visually inspecting them....
Personally, I would have put the valves on and then just taken them in and asked for a fill. Given what the OP says he did and asked for, $38 per tank for a VIP and a fill sounds pretty normal, to me. Not knocking the OP at all, by the way! He AND the shop both sound pretty reasonable in their actions, I think.