This is wildly random.
You can:
Market easy targets for converter fodder or inf
Buy dirt cheap recipes, craft, convert in-group, then catalyze (which can actually be massively cheaper than other ways of getting things)
merit buy
farm
moar market
I can market up 10-20 mil inf in about 15 minutes or less of putzing half afk near a workbench w/ /ah access.
Market is idle money. Merits can be turned into mass quantities of inf used appropriately with converters and _patience_.
It is totally reasonable to spend 10mil inf + a ton of merits turned into converters to build an entire toon, over the course of a few weeks. Merits are easy to get, at 20 per pop per week for the Signature Story Arcs, starting at like level 10. Plus monster hunting teams for 6 per, and 10 for first kill of adamastor for the day.
VERY EASY to convert easy grab merits to huge inf stacks.