Q: Is it normal for the Check Engine Light to come on once a vehicle has reached a certain amount of mi?

My Check Engine Light has to be reset everytime my oil is changed. But after 2 or 3 days, it comes back on. Sounds like an electrical problem. And the gas light constantly stays on. So now I have to set the "trip" so I know when i am due for fuel. How can i get this repaired without it costing me a fortune?