I think the mobile idea is awesome! Opening a store would just provide you with a whole bunch of overhead that you can't really afford when you're starting a business.

Plus, as you said, people are really busy!

I think you should go for it. Also, having a website so that people can check out what you have (and maybe tell you in advance what to bring) is going to really be great.

My only concern would be the fuel charge. With a store, people can walk in, walk around, and not buy anything. But, it seems like you're going to charge them either way... that may not go over too well but try it and see :)

Good luck!
~~~~~~~~~~