Before I tell you what it means, have you misshifted at high rpm at any time before this happened? If so you might have a bent valve, causing the misfires.
Anyway, misfire means fuel is not combusting when they should be, so you lose hp, efficiency, etc resulting in slow damage to your engine.
Your mechanic should have been able to explain what needed to be done pretty quick since many consumers do not understand what a misfire means and what needs to be fixed; if not you better find another/better mechanic.
This is what I'd suggest looking at. If you decide to take it to the mechanic, you can compare what I suggest and what the mechanic does to make sure he's not ripping you off. Of course, I may leave one or two things off because there are so many ways.
1. Check spark plug. If it needs to be replaced, make sure to get NGK iridium or Densos because bosch, autolight and etc just doesn't work with hondas.
2. Check/replace coil packs
3. Your oil ring in the spark plug tube might be bad. You or your mechanic needs to do a compressions test to check to see if the oil ring has gone bad. If you find that oil ring is the problem, just replace that and spark plugs and you're good to go.
4. You have a low mileage for a valve adjustment. But like before if you mis-shifted, you should have it checked to see if the valves are bent.
I think I've hit the major points to check misfires. I don't think the repair cost should be a lot, if the valves aren't bent.