Why aren't there any Centering Prayer studios?

Ok, quick quiz - raise your hands if you know someone who claims to be Buddhist.  Ok, now raise your hands if there's a Buddhist temple with 50 miles of you.  My guess is that most everyone could answer positively to the first and much fewer to the second.  So how exactly does Buddhism spread?  And more importantly, your friend who says they're Buddhist - what does that mean exactly?

image from mydeepmeditation.com

Now as far as I can tell, the number of people in America claiming to be Buddhist is increasing.  Wikipedia
 (I know, but this isn't for credit, so deal, ok) says there are between one and a half and six million self-identified Buddhists in America whereas I'm guessing 50 years ago they could probably be numbered in the thousands, with almost all being ethnically Asian.  So how does a religion with little or no infrastructure grow by millions, while Christianity, with a branch office on every corner has declined by many millions in the same time frame?

It seems to me from my own brief immersion in Eastern religion long, long ago (Taoism for me, I like to be different) that part of the appeal was an attraction to a spirituality divorced from a largely unattractive cultural Christianity, part of it was its lack of organizational structure, and part of it was a young person's desire to differentiate myself.  I never pursued it in depth, but I still own my copies of the Tao-Te-Ching and Chuang Tsu, where they sit in my priestly office and there's a reading concerning death, that I still find very comforting.

But I also wonder to what extent, eastern practices are attractive.  I found Taosim through karate, and most serious Buddhists I know meditate faithfully.  The entry way to Eastern spirituality, at least here in America, seems to be through taking up a physical manifestation, a discipline.  I'll throw in Yoga as the most successful of these eastern spiritual practices.  Now, not everyone who takes up karate gets into Taoism, but there's no denying that these activities operate on more than one level (double ditto for Yoga).

So, why does most Christian evangelism start with convincing people of our doctrine?  And further, why do we primarily offer only our devotional life as our entry way?  Are there other Christian practices than worship that might be an easier gateway?  Could we reorient our churches to being homes to different spiritually-based activities (that people pay for, btw) that would be a boon to the spiritual life of the believers as well as offering something meaningful and beneficial for the agnostic or spiritual seeker?  Maybe entering into faith wouldn't seem so intimidating.  Jesus tells the parable of the sower, but who says the seeds have to be asking people to swallow the wholly grown plant?