its super cheap and super easy to make.
make rice, mix with a little bit of vinegar and maple syrup (or honey)
get a thing of tuna. drain the can. mash in a bowl with mayo and soy sauce
take some plastic wrap and put it on a plate
dump half of the rice on the plate and put tuna in the middle of the rice
put the rest of the rice on top
wrap the whole thing up with the plastic wrap and bang it into a triangle shape
unwrap and add sesame seeds and seaweed flakes
tadaaa!