I don't know if they can help, but I have used smsgui.com's services as a gateway and for sms marketing campaigns.
Check them out. I don't think they do the premium sms stuff, but for the services I have used them for, there is no setup costs and I only pay for individual texts sent. So no minimum order. Plus pretty decent rates world wide considering that there is no contract.
http://www.smsgui.com
Let me know what you think...