Sorren said:
I'm trying to dump XPs altogether. I'd considered doing something like requiring the loss of permanent hit points somewhere along the lines of -1 per 500xp spent. Power componants would reduce or eliminate the cost.
I think the easiest two ways to do this are:
(1) As suggested by Markn, keep track of the total Xp spent and sometimes they result in a level less than the party. The effect is the same as normal rules, but you're not completely dumping Xp in a way.
(2) Replace the Xp cost with Gp cost. Somewhere it was suggested a rate of 25 Gp / 1 Xp which is very high, because for crafting a magic item it makes it 50% more expensive than to buy it! Unless you want a very low-magic campaign, you should use a lower rate.
I like the suggestion of aging, although that is going to be more difficult to handle.
Finally, for my upcoming campaign (next year) I have already decided to be very free for both treasure and experience, IOW money and xp will mean nothing. It's not easy to come up with a replacement to keep magic item creation and casting some spells costly.
For item creation I have other ideas I won't mention here (because they will NOT work unless you also ditch money completely), but they seem to solve the problems. For spells, the idea which is currently on my mind is
(3) For each Xp required to cast the spell, you have to way 1 day before casting the same spell again.
The rate 1 Day / 1 Xp is extremely high for high-level spells. For example, you would need to wait 5000 days (more than 13 years) between casting 2 Wishes. This seems unbelievably long of course, in fact I will probably change it to a lower rate. On the other hand, it would be interesting to stretch in-game time that far, because usually the players have the feeling that their characters don't really age, that they go from lv 1 to lv 20 in a matter of a couple of years.