I've got a friend who is the manager of a local Pet Depot. They don't carry saltwater, but she said she could order for me at cost. I haven't had her order anything for me yet, so I'm not sure about the quality, but she can get me a few kinds of crabs/shrimp for fairly cheap. For example, anemone crabs, arrow crabs, sally lightfoots, red hairy hermts, blue knee hermts, scarlet reef hermits, camel shrimp, CBS, Monkey shrimp and pepermint shrimp are all under $4. They might make a good treat for my eel once or twice a month. Just not sure if they offer any nutrition or not.
I can also get several smaller fish for cheap as well, but I'm not sure if my eel would eat a smaller fish (never had one in with him so I don't know). The last thing I want as I build my tank is a couple of territorial damsels in there. I know my lion would probably take care of them, but the lion is a ways off in my grand plan yet.