XP value for "+1, +2 vs..." weapons

[Frost]

I realize that the "Bane" category typically fits the bill for the special purpose items (e.g., undead bane, etc.). But I've always liked the old school "+1, +2 vs [monster]" or "+1, +3 vs [monster]" without the +2d6 damage of Bane.

Anyone have suggestions for XP value?

I was thinking I would just total up the bonuses, so a +1, +2 vs monster weapon would be 1200 XP and a +1, +3 vs monster weapon would be 1750 XP.

Thoughts?

[alcyone]

I'd probably average the bonuses. "vs" is a limitation on the higher bonus; it's not as good as a sword without it. This assumes a +2 sword vs everything is better than a +1 vs everything, +2 vs. one thing. Sort of works. Might weight the higher bonus more.

So:
+1: 250xp
+1,+2 vs monster: 500xp
+1,+3 vs monster: 725xp
+1,+5: 1375xp
+2: 750xp
+2,+3 vs monster: 975xp
+3: 1200xp
etc.