You can go to Ebay or other internet sites and buy a ring replacement yourself. For example :
Chainrings | Chain Reaction Cycles
Make sure the tooth number and boltCircle number match your original, broken chain ring. I have never replaced a ring myself so cannot speak to that. But it seems like an okay job with an allen wrench. As you can see the ring themselves aren't cheap either. So maybe it makes sense to buy a new crankset. But beware, make sure it is compatible with your bottom bracket.
If it gets too complex you might need to seek a more reasonably priced bike shop/co-op.