Nearest Ikea is about an hour and a half away from my house. I know HD has some off the shelf countertops that are not that heavy that I can carry while staying under my 30 lb weight limit. And only 4 miles from home. I could see if they can order something even lighter.
As for building my own from plywood and formica, formica is not very cheap. Last time I talked to HD about a roll of it, the price was around $150 for a 10 foot roll. I can deal with the extra weight of a prefab and get one for less $$. Besides with just the wife and I, we don't even come close to hitting our GVWR when we are loaded up to go camping.
But on the issue of it being a RV supplier only or from a big box store, I gather I could go with one from a BB store then. At least I won't have to pay go to a Retirement Void supplier to get the countertop. Good to know.
Now to get the Boss (wife) to make up my mind on what top we want.