Antivirus aint cheap

I was talking with an IM vendor today. We’ve got a budget to implement IM antivirus this year as part of a LCS implementation. The Instant Messaging antivirus would protect LCS, AIM, Yahoo Msg, MSN Msg, ICQ and down the road Google Talk. The price he quoted, I’m pretty sure is more than we pay per desktop for our corporate antivirus. I’m all for layered protection, but this is getting kind of expensive.
I’m thinking two things, 1) http antivirus is more important than IM antivirus, so perhaps my money should be spent there. and 2) why spend money for gateway products. They dont travel with the user to protect them when they are on the road. Perhaps the money should be diverted into a HIPS product with a good track record with zero day worms.