Merkhants
Merkhants, also known as Misers, subscribe to a simple philosophy: Money is power. The accumulation of raw material wealth will lead to dominion over the multiverse. A berk can run the whole bloomin' cosmos if he's got enough jink to buy it.
Most Merkhants work alone, although they hold irregular meetings to discuss matters that affect business as a whole. They'll help each other out - for a price. Some Misers work only through legitimate business channels, but many know of the massive profits to be had from doing business in the black market.
The Misers are strongest in the Outlands, as trade from all over the planes crosses this "middle ground" at one point or another. They're allied with the Believers of the Source, since they feel that mortals and powers are the same except for the amount of jink (and therefore power) they've got. Misers are also on good terms with the Fated. On the other hand, the Merkhants don't care for the Guvners and their trade-restrictive lows and tariffs. The Ciphers find the Misers' obsession with material wealth distasteful.
Eligibility
While a player character can become a Miser, it is very difficult. In Sigil: Planar Legends, a single jink is the equivalent of a copper coin and a Miser has gold and platinum in such an amount that they are wealthy beyond measure. Dropping tens of millions of jinks would be no concern at all and just a minor 'drop' in the proverbial bucket of their wealth. Additionally, such a character would be expected to have ownership (or high levels of investment in) of several prolific businesses, a vast social connection that includes both influential NPCs and PCs, and likely a strong and widely known role in helping to manage some important city in the Outlands, such as being a member of the Tradegate Council, for example. Becoming a Merkhant also comes with the realization that the character has essentially risen to a state above that of Planeswalking; wealth is power; and they would be much more prone to hiring their own team of Planeswalkers than spending their valuable time doing something reasonably pointless like going out to adventure for what amounts to petty change for them.