I am interesting in getting my ACE certificate at some point but I think (for me) I am doing it as something on the side. I'd like to teach a class and coach a children's swim team so I am not interested in doing this as a career but something I was to do for ME (and for fun). As you pointed out, it is very expensive.
My advice would be, if you're looking for this as a career, you're going to have to be very investing in improving your skills, and marketing yourself. Very few people I know can make a living off their exercise certification alone (Obviously, there are exceptions).
If you can't imagine a world where this isn't part of your everyday experience, and you'd be happy just making enough money to cover your certification costs and have a day job, then I say go for it. If you want a career in this, then maybe you should look at a community college program in exercise physiology?