I have there old style scissor tranny jack. It has paid for itself more than once. Not much to go wrong with it other than caster mounting nuts coming loose. So I tacked a weld on and they never came off again.
I've had one of them over 15 years now, still working perfect!
I do wish I owned the jack johnvh bought, but there's a rental place just down the road that has one for $10/4hrs, or 15 a day. Hard to buy one for that price!