This is an interesting item, but I'd say nothing more than 2-3k.
Only reason I say that is you can get better stats from using a 20/20 divine ankh and 20% recharge smiting rod, or even better then 20/20 smiting collectors staff.
17% faster casting speed on divine skills for a smiter is really nothing when you are spamming divine boon with a 1/4 sec cast time.
Gold Smiting Staff
Levi Garett