I never seem to get around to it. I did use a liquid fertilizer on a small section of the garden this year and fully intended to do the rest, but there's never enough time to get everything done.
If I ever do get really efficient and start fertilizing on a strict schedule, I should be able to get along for years with just the stuff that's already on the garage shelves. I have no problem buying all types of fertilizer. Actually applying it is a different matter, however.
