Never paid any game more than 20€. (at least since euros exist)
And even then, i rarelly go that high.
Every single game go down to that price or often lower after a few years. It even go down faster now with steam and other online-stores. I stumbled across many HD games for less than 3 €, the last few months.
Beside that, buying many games on the launch date will make you feel cheated, as you will have to pay again for the add-on/expansions/dlc. If you wait enough, they would be already included when you buy the main game.
If is safer to wait at least two years.
By the time the price go down, you'll have plenty of time to discover some oldies, that you haven't tried before. Many great games were released in the last 30 years... (some of them are even free now)