Shira,
I don't want to throw cold water on your enthusiasm but don't make any major monetary investments until you're certain your phone is going to be ringing off the hook. For example, to go from a couple of calls a day to 30 to 40 isn't a fact yet, it's a hope and if the calls come from an expo, the duration will usually be short term. You'll have a lot of hits right off the bat, and then they'll taper off and likely be slightly more than you currently get. Each expo you do and as word of mouth takes over your business will grow steadily and you can adjust as you experience the growth...don't spend and make committments based on what may be nothing more than a flash in the pan.
Good luck