Fees/fines vary by municipality. You would be exposed to doing work without a permit, the cost of the actual permit and, worst case, having to rip it all out and have a licensed plumber/electrician do it again.
I've heard most municipalities around my area no longer charge the work without a permit fine. They just make the homeowner buy the permit. I wouldn't think they would require a redo for work that is readily visible, but it seems like your inspector is on the extreme end.
Try asking for forgiveness first since it is a trivial amount of work with low complexity/skill required. Fallback to appealing to the municipality's manager for forgiveness. Last, offer to buy the permit only if they are charging a fee for work without a permit, but that will require a licensed plumber and electrician to inspect which will be another fee on top of the permit. Plead, "I didn't know I couldn't do simple work like this in my own home. It's done all the time!" It might work.
Next time, don't be so chatty showing off to the inspector everything you did. Remember, "You have the right to remain silent and anything you say can AND WILL be used against you." when talking with a government inspector.