Budget for Conference/Symposium

Hi, just wanted to get some idea of how much immunohistochemistry and histology labs budget for going to a Conference/Symposium or anything similar per year. My supervisor is trying to get the Director to budget for these kind of things and would like some input from other labs to show him. We currently have 3 techs and will be increasing in the next few years. Also are more than one tech allowed to attend each event? Thanks in advance for any info you are able to share.