It’s a misconception that fish is expensive. If you have a good local market or fishmonger then go and browse what they have on offer and I’m sure you’ll be able to source something affordable. I bought a whole smoked trout and a blue grenadier fillet from the Queen Victoria market for only $11.
I try, sometimes unsuccessfully, to buy sustainable fish but depending on where you live in the world the types of fish available will be different. A great website if you live in Australia is Good Fish Bad Fish which outlines which fish to avoid and which fish to buy.
The one piece of advice I do have is never to buy prepackaged seafood – it is slimy and smelly and is often shipped in from abroad where fishing practices leave a lot to be desired.
Of course, for those of you who are inclined to do so, catching your own fish is the best, freshest option. The pitfall of this is we don’t all live close to the ocean or clean rivers, and most of us (me included) definitely don’t have the time or patience.