First $.75 I ever saw out there was Galaxy Force 2, which was *entirely worth* it. I'd still pay that for a round on one of those if there were any still operational. I've heard they were prone to frequent breakdowns, and my experience was that there were 50-50 odds on any arcade visit on if the machine was going to be operational that visit.
I've also heard DDR machines require pad repairs about every three months on average.