of the fans. Basically it takes a screwdriver and matching wire colors. The important thing is to turn off the power at the breaker/fuse panel BEFORE you touch the fan.
The instructions are generally pretty clear about what to remove and what to replace. It might, maybe, be easier to take the entire fan down to work on it but it can be done using a ladder. Just make note of which wires connect where on the fan BEFORE you disconnect anything!
I'm not sure about the cost of the new receiver, I never looked. I wouldn't be surprised if it was a good $20-$30 or so. Just be sure to have your model number with you since not all receivers are the same or fit in the same place.
It's not a hard or dangerous repair as long as you follow the instructions to the letter.