SO, i got two oscar fish thats around 10 inches .. a albino one and a tiger one... i was trying to sell it and i went to my LFS and he said he will give me 40 store credits is it a good deal or too low?
You're lucky to get that, not much demand for big oscars due to how common they are, their quick growth rate, and how many people buy them without knowing how big they grow.
I agree with everyone else. You are very lucky to get $40 in store credit, no matter what size the fish is. Oscars are sold in basically every pet store around, (including the chains) to people who have no idea how big they will get. Stores get 8"+ Oscars in every week, some everyday, from people who are unable to keep them.
Take the credit and run!