There is an upper limit, but I’m not sure what it is. Like Ulf Bengtsson, I’m currently pledged for $450 for God’s War, with the caveat that I may not stay at that level by the time the kickstarter approaches close. I probably dropped close to that on the RuneQuest Classic KS, but I have this weird fascination/nostalgia for all things Glorantha that totally triggers my FOMO.
I can’t think of any other KS where I’ve pledged anywhere near that much, though. $100 is probably the sweet spot; I have to be really interested in something to approach, much less exceed that amount.
That said, if you compare my average RPG spending to the kind of cash demanded by, say, my guitar hobby, it’s chump change. You couldn’t buy a single effects pedal for how much prestige RPG backer levels cost. And getting a really nice guitar for under $2,000 is generally considered a good deal.