In guild wars I purchased 4 extra character slots and 4 extra storage panels. I don't quite remember what that adds up to, but yea it was well worth it for me, since I put over 2000 hours into it. As for F2P games, if I play for a while and I am enjoying it, I will spend up to 50 USD on the game, depending on what it is. LoL is the worst enemy of my wallet....their microtransactions are really enticing. As for others, usually no more than 30 USD. And for TF2 I only buy the occasional key if I have a crate that I REALLY want something from.