Oh dear gods yes!
I have a slightly longer head shape than most people. It makes buying motorcycle helmets really hard and finding a truly good dive mask impossible. I have tried probably every brand and price range, and have to settle for just smearing on an absurd amount of silicon grease all around. I still experience a constant but slow leak the entire time, and generally have to clear my mask every 3-5 minutes no matter what depth I am at.
I have been searching for a good fit since 2005 or so. I have tried every tip and trick out there. Nothing. My personal mask fits far, far better than any rental one, of course, and I spent a lot of time picking it out. It really is the best fit on the market for me and it sucks.
Many people on here have chimed in about price concerns. I'll up the ante: charge me an absurd price if you have to, just bring this product to market! For those of us with nonstandard face shapes, this minor annoyance builds up, dive after dive, year after year. It cuts into my time underwater (rough guess, 5% of my time underwater is spent messing around with my cursed mask.)
If I figure the cost of dives since I bought my current mask, that time spent with an ill-fitting mask has robbed me of enough cash to buy a wireless nitrox computer, a wetsuit and a mid-grade BCD.
I don't WANT to spend hundreds of dollars on this, but honestly, I would. Especially if you could make a bunch of mask skirts at once for when they eventually wear out.