Yes they do exist. They just don't know it yet! I've never gotten into the age play aspect but I've had it offered to me by women that discovered I like to wear diapers and assumed I wanted to be babied.
I go back to the days of DPF when it was produced on a mimeograph machine. In addition I've been a cross-dresser almost all of my life and between the two fetishes, I've had contact with hundreds of like minded people over the years. It's given me the opportunity to put a lot of them straight on finding a woman that accepts their fetish.
I have yet to talk to or correspond with a man in a successful relationship with a woman that met that woman through a contact service, whether it was a club sort of thing like Diaper Mates or Craig's List or any place else where you post an ad or answer one. And AB's are by far the worst at chasing off the woman that join. So many women drop out in fear when they get inundated with requests to be a mommy when their profile clearly shows that is not their interest.
But there's always the exception. I know of one woman that had a 'little one' of her own and advertised for playmates for him and she didn't charge a thing. Again, that is the exception. Almost all "mommies" advertising their service are doing so as a business. I've seen rates from 50 for an evening to 500 for a weekend and that was quite a few years ago. I'm sure by now there are some much higher.
Here's the advice I give to anyone with a fetish that is looking for a relationship and not just a weekend fling: Start the relationship first. Show her who you are and why she should consider you a 'keeper.'
Then at some time when it becomes serious, broach the subject in a roundabout way. If you do it right even if the relationship doesn't work out, you'll have a friend that shares your secret and an amazing number of women seem to like that. In addition, if you nurture the friendship, you'll have an agent of sorts. Among themselves, women talk about sex as much as men do, if not more, and are actually more explicit. So they know who among their friends is likely to be acceptable to the things you want to do.
Here's what works for me at my age. When I meet a woman I'm attracted to and start dating, almost always at some point after a few dates they'll somehow bring up the subject of marriage. These are all mature women that are either widows or divorcees and they want to have some idea how serious you are about building a relationship that could potentially turn out to be permanent. Generally I make a very good impression on a woman and she'll make a comment like, "How come you haven't remarried?"
What she's fishing for is to see if you've ruled out ever marrying again or are really gay or whatever it happens to be that you seem like a great guy but are available. So my answer is, "Too old, too poor, and too kinky for all the women I've met." Then I'll try to change the subject and let them stew on it. The "too old" part is meaningless because we're usually near the same age. "Too poor" will cull out the ones that are looking for a man to pay their way on cruises and vacations. And the "too kinky" piques their curiosity beyond belief. Some will deman an immediate explanation but most want to think about it first. Eventually within a few days or so they'll find some way to ask for an explanation. When they do, I laugh it off. "Don't worry, I'm not into whips or chains or pain or anything like that. I've just got a history that goes back to the way my mom raised me that some women like and some don't." Then I change the subject again.
Each time you leave them with unanswered questions, their minds will come up with possibilities that are way more unacceptable than a man that likes to wear lingerie and wet diapers. So when you finally do give them the details, it's almost always a relief to them that you weren't the pervert that they'd imagined. Then I ask if they really want to know or just want something to tease me about and every time we wind up in an intimate discussion where I get to explain how my mom kept me dressed as a girl and in diapers for most of my childhood. By the time I'm done, they realize I'm harmless and that there was really no other way for me to turn out considering the circumstances that were beyond my control.
The woman I'm currently seeing bought me lingerie for Christmas a couple of weeks back and the first time she spent the night with me at my place she told me before we went to bed that if I was more comfortable wearing a nightie that I should and she'd like to borrow one. And this is a woman I met at church.
So again, build the relationship first. Be the person she wants to have a relationship with and in today's world, most women are well aware that almost all men have some sort of kink they'll have to accept. It's part of the package and the more the whole package has to offer, the easier it will be to get the acceptance you want.