Membership level by invite

If Im being stupid tell me as I probably should know this by now...

Im building a free site but want to limit things like blogs, groups etc to a higher membership level only.

Thing is, if I create this level then anyone can select it when they create an account.

I dont want to charge for the level.

I want to be able to make the level invite only...

Any suggestions to do this?

Most probably Im just having a brain blank day...

Ideas?

anyone?

Hello you need a custom module for this. You can make a bid on a job page