I can get KILZ reasonably cheaply at the local Wal Mart. Or Home Depot.
I plan (now) on rolling on a coat of sealer (or spraying with a Wagner Power Sprayer) a coat of sealer on the walls, and then painting the floor with an epoxy paint (I forget the brand, its in the garage now, also from Walmart) In a day or two when that all is dry, I'll go in with the blue, and then add in the white clouds and some grass.
Indeed, many gearages I have seen are trashed looking, but if you have bare walls, and you put your oily hand on bare dry wall, forget about removing the stain. If I seal/paint it with a good latex enamel (assuming that isn't an oxymoron) I should have a fighting chance at getting the stain off.
The hard part will be the ceiling...
Thanks for all the help, no offense taken, to each their own.