Wedding planner with a question for other planners...?

It's kind of hard to say whether they're legitimate or not; some may be, others probably are not. What I would suggest is to respond to them and say that you will not accept a credit card deposit, but you will accept PayPal - that way, you actually have the cash, and you can go ahead and do whatever you need to do without having to put yourself out by paying out of your own pocket. If they refuse, or never respond, then you'll have your answer.