OLD_Augmenting

Because the gods of Chromatia are obsessed with new ways to tear apart the fabric of reality, and I have no interest in stopping them.   -Ingleheimer Smith
Yes, in Chromatia, it's possible to add +1, +2, or +3 upgrades to any equipment in the game, including magic items that normally can't be upgraded in more standard worlds. Yeah, we know. Shut up and enjoy the needless buff because rule of cool.   Adding a +# enchantment to the item must go through Ingleheimer. You don't have to RP it, but it's not a service you will find anywhere else in the world, so don't go RPing it somewhere else. To upgrade an item, you must pay Ingleheimer the item's base (or adjusted) cost, plus the cost for the upgrade in question - unless you already own the item being upgraded, then all you have to pay is the upgrade fee.   A +1 enhancement costs 500 gp, +2 5,000 GP, and +3 50,000 GP. Once the commission is paid, Ingleheimer will effectively need to work some magic hocus pocus to reconstruct your item at the molecular level and insert the enhancement without otherwise destroying its existing enchantments. It's a very delicate process that involves a lot of hammering and smashing. Also, no, upgrades don't stack - if the item's already +1 and you get a +2 upgrade, the item is now a +2 item.  
Okay, this time, let's say I'm some kind of slippery thief who really, really wants a set of +3 mithril plate so I can flex and dodge roll for days without ever having to worry about clanging my heavy armor around and getting everyone's attention, because again, I'm a thief and can't be seen but I really don't like getting stabbed when I'm caught.   The base cost of plate armor is 1800 gold pieces. Mithril armor is a non-attunable uncommon magic item, so that tacks 250 gold pieces to the price, for an adjusted cost of 2050 gold pieces so far. A +3 upgrade is worth 50,000 GP alone, so, to get my +3 mithril plate, I have to fork over 52,050 gold pieces to get the job done.