Get a minimum of three bids. Estimates for an average-sized job should be within a few hundred dollars. Be suspicious of anything that is substantially lower or double the price of the rest, and watch out for hidden fees, like charges for travel expenses. They could be signs of a home improvement scam. A good plumber will not nickel and dime you like this, and many of us will offer free estimates.
There’s often an Allen wrench that comes with the garbage disposal. I keep it under the sink. When the thing jams, follow the directions in the manual, and I won’t need to come out. Another plumbing tip, don’t believe the myth about putting lemon peels in the disposal to make it smell better. That will just make it jam faster. These are the things you should never pour down the drain.