I'll bet the OP wants something easy, long lasting & cheap as well. HA! Good luck. Not going to happen.
I am in the middle of giving my 12 year old 5er its annual waxing right now. It is a full 2 day job. The gelcoat is in great shape because it has been taken care of since almost new. No chalking. Spending 7 months of the year indoors helps in a very big way.
My wax of choice is the Meguires flagship. It does nothing to remove dirt, stains or chalking but is an excellent protective wax hence only the need for once a year. Twice if the 5er was outside year round.
If you have neglected your gelcoat then there is no easy or cheap way to restore it. You have to get rid of the chalking before even thinking about waxing. A cleaner wax will remove minor chalking but will not hold a shine for long, never mind what the claims on the bottle are.