Gamertag not allowed league tag

There are only 2 ways to get a free gamertag change. 1) If the system chose a random name for you, you are allowed 1 free gamertag change within the first 30 days of having the tag. 2) If the tag violates the code of conduct the enforcement team will issue
a forced gamertag change.

Unless you fall into either of those catagories, you'll have to pay the 800 points to change your tag. Spaces are allowed.

The gamertag in question is already taken. If you remove the space between the "avenger" and the "i" the tag is already in use. Putting a space in the tag will not allow you to use it.

No, you will not get in trouble for this. Licenses for most DLC (avatar gear is the most notable exception) is granted to the console (allowing all gamertags on the purchasing console to use the content) and to the gamertag (allowing that tag to access the
content anywhere as long as it is connected to XBox Live).

Afraid not. The gamertag system was changed a while back to allow people to have the same gamertag but if the tag you pick is already in use then it will have a suffix & numbers after it.

If you want to change the tag you have now then you will need to pay,there is no way around this.

Buying/selling of gamertags is not allowed.

The tag system is in use on other Microsoft services so even if they are not in use on the 360 they may be in use somewhere else. The system also doesn't see things like spaces as different gamertags. So if you were to look up 'gamertag' it may show as available
but would be taken if it was spelled out as 'gamer tag'.