Globat.com offers a 30day full refund service, which although it isn't the same as a 'Free-Trial', I would be very suprised if you found their service dissatisfying. I have hosted with them for months and have no problems at all. Their GigaByte package also often has HUGE discounts where you can pick up 2500mb web-space for $1 a month*.
I reckon you could probably work something out payment-wise with their sales department, so give them a look. They also support live chat so you can sort it out in an instant!
www.globat.com is my reccomendation!
~Equinox
*Terms and Conditions would of course apply!