So if I wanted to allow human classes to take a Dark Creeper option (fighters, Theives, Assassins mostly) where they had Infravision ala Gnomes, what would be a good XP value for that? I mean the XP value of the High Elf Option for elves seems a bit low for Infravision.
In a custom class infravision is worth 1/2 of a power for every 15 feet of range, in the Player's Companion listed as ranging from 30 feet (1) to 90 feet (2.5).
Depends on the class build how much that ends up costing you. The thief, for example, would give up 3 of its skills to purchase 90 feet with a zero-sum change. The Fighter would need to trade-off out of Fighting value 3 powers for 450 XP, and assassins would need to trade skills or different parts of their Fighting value for it, at variable XP costs depending on what's done.
As an actual add-on would be a bit dicier as it's outside the class build process in the PC - it's 75XP per extra power, so 225 XP for the full infravision, per-level-per-level, or make everyone spend a Fighting Value tradeoff at 150XP per, for 450 per-level-per-level.
225 xp sounds good to me. Mostly I'm thinking of using them as NPCs so the XP value doesn't matter too much, but I thought it might be interesting to offer as an option.
To Clarify I'm running Against the Slave Lords, except set on a dying earth type setting, and I'm thinking of replacing the Drow with Dark Creepers, I'm already replacing the Half-Orcs with Hobgoblins who can pass as human.