The ability to add options to products that modify the price, but don't create a new variation. Also allowing certain options to only appear depending on what option has been selected before.

Obviously this would mean need for more than 3 product options as currently allowed, and more then 50 variations in total. Just don't make a separate variation for each option combination, as I don't fancy going through 500 product variations 1 by 1 to change the price and miss 1, although I guess this is why it's limited to 50 currently.