Me and my wife share basically all of our assets so I can't really estimate without her.
At any given time we probably have at the very least 1 million in liquid assets across our 12 mules and try to keep a decent amount on our persons.
In gear alone I have trouble estimating really. Several of our pieces are huge cash pieces like Astral Rings and such. If I had to estimate I'd have to say we have between 15 and 20 million gil in equipment alone and perhaps even more. Keep in mind each of us works on several jobs and keeps a lot of extra (mostly HQ) equipment on our mules for our lower level jobs.