When I started up back in 2001 I decided to start a 14 day free trial. I set up PayPal to have a zero charge for 14 days and then start auto recurring unless they contacted me to cancel. It worked well... very well. That was 2001 though and I am not sure how that would run now with the hosting market being a lot busier now then it was then.

It wouldnt hurt to try although I would be aware of fraud these days and spammers wanting an account for free real quick. I didnt have that issue back then. To get over that part maybe you should do manual account creations.