[...]
Personal and Corpwide custom suit/vehicle paint schemes. Can be made available in tiers e.g.:

I) Generic colors from limited pallette
II) Above with extended pallete and simple patterns (classic camos, fractals etc.)
III) All of the above, alternate material shaders (flat/worn, rusted, carbon, goldBlink) and the ability to paint parts individually for "one of a kind" designs (client performance concerns?).

Alliance ads:

I)Alliance Banners in PC/FW war barges during selected timezones (open corp info when interacted with)
II) Corp/Alliance description on Merc quarter TV

Making all of those tradeable, consumable items (like PLEX) would allow corp leaders to pay for them through taxes and hopefully alleviate the "who's paying for it?" issue. It keeps those features from being locked behind a solid paywall aswell.

To get to the topic CCP could also bundle these with subs:

"Mercenary" sub nets one 30day booster and tier I personal colors, Some AUR.
"Veteran" sub includes one 30day booster+ tier II personal and tier I corp colors, Some AUR
"Elite" sub includes tier III customization and banners (+benefits for corpmates? 1day boosters, even?!).

...............................

Or, you could use the options we already have. A good one is, you know, making it a BPO. Works just like in EVE.

I do not like the idea of paying for each individual liter of paint for every suit i lose. It just sounds...exploitive...furthermore, it would discourage inferior players from spending AURUM on custom skins, as it would cost them more than it would experienced players.

Since it offers to real tactical advantage, a subscription, say $5/month could be paid to paint any piece of gear any color that a player wants.