Maintenance depends on many facts. I mean depends on cost of your domain registration, SSL certifiate type etc. The site runs on Microsoft Azure where you can choose your monthly limits, but even with pretty high performance hardware the prices aren't too much. The Google Admin account cost 40eur or something for a year.
As long as you are a seriously interested I can offer you free support for a few months, until you can run it by yourself
For more details contact me on Skype : g3rszpi