We will not raise the subscription fee above the current value of 20 Euros/year. If anything given a sufficient amount of subscribers, the figure ought to be lowered. NG is not run for commercial purposes.
As to costs of web hosting, remember there now is VAT to be paid and that the server handles a significant bandwidth load. There are a lot of other aspects, domain maintenance, and server features required that reflect in the price. The general price hike has been substantial over the last years, though.
The admins do pay attention to suggestions provided here and elsewhere, but in the end, economy will control the future of NG. A steady trickle of subscriptions is preferred over donations and in fact we would not accept the latter.