Honestly, its a great name - I personally love it. Perfect for a marketing company, because thats such a good catch-phrase right now.
Value wise, really is going to be tough. But here are some recent sales comparables (check my sig for more Domain Sales history)
buzzbloggers.com $250 2007-04-04 Sedo
startupbuzz.com $80 2007-03-30 Sedo
buzzable.com $1,250 2007-03-20 Sedo
techbuzz.net $1,280 2007-03-13 BuyDomains
So, the keyword "buzz" can be hit or miss as demonstrated above. I think Buzzable is a great brandable domain name, but its a 1-worder and parked, so it may be recieving good traffic.
StartupBuzz.com reminds me of the closest one to yours, although I think yours is substancially better. I would definetly value it in the low xxx reseller range. (This is where you would sell to a domainer) Now, to an end-user, you never quite know, it could go as high as anyone is willing to pay.
The catch? You have to market a domain name to the marketing industry.
If you wouldnt mind sharing, what was your offer? I may be interested in purchasing if its within reason.
Justin