We just did our first show and we did that for free. She was pleased at how well it went. I mentioned to her the thought of doing birthday parties and how she could receive some extra cash, but i did not get much of a reaction or a response.
Yea, starting out is tough. You can't pay what you don't have. First try to get paid for everything. Second, many people who start a business, deny themselves a paycheck but still pay their staff. You might have to include twenty bucks or so to your expenses (for the assistant) even if you are not paid for the show. You paid for your magic tricks, right, so pay for an assistant. She might perk up a little.
Remember stage magic is expensive. The cost of something has to include the cost of everything. David Blaine did not do his magic with a 2 dollar deck of cards; he did it with a 2 dollar deck and a 10,000 dollar camera crew.