A Grizzly 1x30 with a small flat disk (don't get the simplest one, it's junk- look for the one with metal, not plastic wheels) costs less than a hundred bucks, and if you stay the heck off the platen and use good belts you can do one heck of a lot of sharpening with it, and do a good job....if you understand sharpening and knives in general, that is...
I can see why a person might want to put the whole grinding scenario in a trailer, but a table and a grinder that costs pocket change that you can lift with one hand and plug in anywhere is a pretty good option.