I highly doubt that funding a GunZ server is too costly, considering that you just have to manage the matchmaking etc..
I'm down for LBs being cool unique items, I tried to get them for the looks anyway, not for their stats
There can also be other sources of income, like the cosmetic boxes, there's a lot to explore.
You could have custom emotes that you can buy for coins, or via boxes (all that'd require is to strip the message if the player does not own the emote, so let's say the player sends "Hi :premium:!", if the player doesn't own that emote in the database, the message can be trimmed to "Hi !", can also have more dashes, and maybe even reskins of the current donor guns.