As for me, my best advertising is referrals. It is a time investment, yet it PAYS OFF BIG!
As far as a budget, It really depends on the project I am promoting.
I agree Dave, it is important to have a plan and to always be working on TOP of MIND awareness.
Though it is clear from yours and Terri's comments about Listsurfing, that a recommend from the 2 of you is of huge value that cannot have a price tag put on it.