Try searching EBay or look for used car parts dealers in your area or salvage yards. Call them and ask if they have a vehicle like yours and if you can purchase the seat belt.

My Check Engine light is on,Where is the most inexpensive place I can take it to get checked?

You can go to any Advance Auto or Auto Zone and they will pull trouble codes, the engine check light being on indicates there is a trouble code present, for free and give you the readout that will have a brief desription of the problem or the part that is at fault.