Hello what economic control panel (billing, mrtg, etc) for managing dedicated servers do you recommend?

Thanks.

UberSmith is a popular control panel for that sort of job: http://www.ubersmith.com/

eJadSPM (www.machsol.com) also lets you setup dedicated hosting packages, bill them, manage datacenter, IP allocations, remote server management, and order forms. You may want to check it out.