If you browse to the revision-control appliance page then you can download it in a variety of formats for free! Obviously you'll need to provide your own hardware or VM environment to host it on but it's good to go.

If you want it hosted in the cloud, then you can use our Hub interface to launch it on Amazon. You pay Amazon directly for the server hosting itself (how much depends on what server, in what region and a host of other factors - see the AWS pricing page and/or the AWS calculator). On top of that is a monthly Hub subscription fee. It relates to the server sizes you wish to have running and/or the level of support you want/need. See further details here.

If you are new to Amazon and you only expect a fairly light server load (you mention 10 users) then you can get one free Amazon micro server for a year (AWS "free Tier"). The base Hub plan (which is also free) supports unlimited micro servers. So if you go that way it could be free for your first year! If you find that a micro server doesn't have enough resources for your usage scenario then you can migrate to a larger server and just upgrade plans appropriately...