They way I wish it worked, although I haven't seen it really successfully implemtented is that instead of paying for a support contract, you could pay for support in a more a la carte manner. Such as say, pledging money to a bug or feature, and the dev team prioritizes based on how much money is pledged for different features and bugs, perhaps with some expiration so customers don't end up paying for a bug that isn't fixed until years later when it no longer matters.