Thanks so much to everyone.
In terms of budget, I honestly don't know. I haven't done this in many years, so am not sure what prices are. The last time I did this was 2005 and I can't remember the name of the caterer I used. He was excellent, though. I wish I could remember!
We had 80 people last time and the cost was about $800 delivered and set up, IIRC. It's sort of a grazing event--the see a speaker for 30 minutes, then network and graze for 20 minutes, then another speaker, then another graze, etc. While we did have some sandwiches, we mostly had things like hummus, baba ganoush, breads/crackers, fruit, veggies, salads, nuts, cookies, etc.