Funny I never saw this post before
Aion costs 12.99 EUR a month if you pay by month and around 11.00 EUR if you pay for 3 months at a time - it uses the same time cards / fairs as lineage II.
If you go on vacation or something you can temporarily stop paying and activate your account again when you are back.
The game itself (standard edition) is on sale for £24.99 (Currently ~27.79 EUR) on Amazon.co.uk (delivery throughout Europe).
There is also a collectors edition which sells for about £79.99 (Currently ~88.96 EUR) on Amazon.co.uk which gives a lot of ingame extra's such as better wings etc (saves you some kinah ingame) on the other hand kinah sells for a bout 4.00 EUR / 1kk atm, making the collectors edition quite over priced (the collectors edition wings give +40 sec flight time, +30 sec flighttime wings cost 900k and +60 sec flight time wings cost 11kk - do the math yourself). Ofcourse buying kinah for real money (RMT) is against NCSoft's policy but I wouldnt blame you if it was just for the wings ;x. The game also features potions that give flighttime (from +12sec to +48sec) so I even dare to say the wings are no real must - at least not untill you hit 50)