After a free trial period I decided to buy mob.is.it and I am very happy about it. It is a pleasure to work with this tool and it is also good for beginners who don´t have too much experience in web designing. The support of mob.is.it is very friendly and they got back to me very fast.
Amazing features for little money
Special pricing for agencies: "pay as you go": $400/year and each mobile site costs $65/once, no other recurring, maintenance or hosting costs (first site included, each site is then yours forever) -- "all you can eat": $700/year or $70/month, build unlimited mobile websites