Trader Joe's has an Italian-style solid light tuna in olive oil pack in the Genova brand. It's just a 6 oz. can, which I'm not sure is appropriate for a caterer. They charge about $1.69 or so, which happens to be about half the price I see it in the "supermarkets" around Chicago. We like it a lot. I have no idea if it's available in more commercial-sized packages.
It's marked from a seafood company in San Diego, so I assume it's a Pacific tuna. They claim it's Dolphin-safe.