Small circulating fan to cool amps


I have two tube amps that are on a rack system with wood shelves. Because of the space requirements of all the components on the rack, there is not as much space as I'd like to see between the top of the amps and the under side of the shelve above. Although I have not had any problem to date, I'd like to make sure it stays that way. These amps do throw a fair amount of heat. Has anyone had any experience with a small fan that could be used for ventilation? I looked at Radio Shack and although they had a number of small fans, the smallest and lightest ones were 12v. I'd much prefer to run off wall current, but I don't have alot of space in which to situate the fan. Their non-battery fans were just too big and heavy. Any suggestions?
frankm1
1) DO NOT try to use the 12V trigger output as a fan power supply: they are very limited output current

2) any cooling fan should be mounted so as to draw heat away from the component - not blowing air onto it
Bob, I was going to ask the same question a inpep. Mainly because for years, ARC used forced draft (I don't know if they still do.)
i would think that forse draft would cause dust to go inside sourse faster,although i have cleaned both pulling and pushing air and they both were dusty,i know when im hot i want fan to blow on me,but im a southern boy ,what do i know?b and bob is right ...no 12v trigger ,use wall wart