Decent & Steady Money Makers?

In GMS, the only way to make any useful amounts of mesos is either by using NX or playing the market. Hackers and exploiters have made any farming/bossing enterprise useless in that regard. As an example, some time before Big Bang I managed to get over 4 billion mesos from a single solo HT run (2 MW30). Now you would not even make 100m without using NX on scissors.
KMS is probably a bit more forgiving though.

EDIT: This does not include any events and what you can earn by those, since that is hardly to be viewed as steady.

seeing how bosses don't drop mastery books in forever, that's out.

I make money in GMS the same way convenience stores make money in real life. I sell stuff that people want all the time (like DM scrolls, cracks, eyes of fire, mitherial & steel plates, superior item crystals, etc). I locate my stores in the same place 24/7 and ensure I never run out of my stock. And just like a convenience store people are willing to pay more if they can go right to you and buy what they want without looking around.

Is that actual fast/decent profit? You just spend all day doing the zak prequests for eyes/DM scrolls? Superiors are basically a dead market atm since no one buys them. Steel plates...don't see why anyone would buy those.

There is truth to this. There's one person in Windia that always has the same FM spot that sells ores/herbalism items, and I always find myself remembering that one. Even if they aern't the cheapest I know that's where they are.

What herbalism items?

This is for GMS... no idea for KMS.

The only way that I've ever had a steady stream of actual net profit is boss runs.

CZAK Solo = 20mins
CZak helmet = 250mil or 300mil (-1%~-2% tax)

PSoK = -200mil or -240mil
Pots = less than 1mil
EoF = -3mil or -5mil
Potential Scroll = -2mil or -5mil

Average 30mil per run. 20mins.

Every run doesn't guarantee payout either. Helmets must be potted + above average to be able to actually sell. Any helmet less than average will never ever sell for more than what the PSoK is worth and potential scrolls can boom a good helmet, thus requiring another run (which means double the costs).

-

Pink Bean Solo = 1 hour
Reverse Armor pieces = 5mil each
Reverse Weapons = 5-10mil each
Reverse Katara = 50mil each
Reverse Cane = 50mil each
Recipes = ~1mil each
MMB = 6mil each
RoT = 3-5mil each

Typical gain = 50mil per run / doubles if a katara or cane drops (very rare though)

2 Energizer = -5mil
Pots = -1mil
All Cures = ~500k
30 masks = -30mil (or spend time farming it.
3 boss pieces = around 2mil each

Cost of the run = around 40mil ish. 1 hour. (or around 10-20mil ish. 1.5 hours).

An especially taxing boss since you need to always be paying attention to what's happening. If you DC or die, you're immediately out of your initial investment and you can't run for another 24 hours. Using a wheel will bring up costs to another 25mil which is unacceptable if you want to actually profit.

-

This was how I made my meso but really the real profit came from people selling PSoK/NX for dirt cheap or I had multiple people come on the run and didn't want any drops. They're huge time sinks too that could be spent on other activities that could potentially get 10x more profit than this (such as merchanting or working).

Atm, the only real profitable boss is Ephenia in Elin Forest because she's a low level boss that drops rings that could potentially become Superior Crystals that would sell for 1-2mil a pop. Zero investment other than time (which isn't a whole lot since each run is like 1 minute long).

However, even Ephenia doesn't bring in enough meso to justify purchasing a Mushy.

a Czak solo I could do but getting a cheap PSOK is a problem. Seeing how the current NX rate is around 1:35 in KMS and you only see psok in merchant shops for double the price czak isn't that possible atm. Pinkbean is out of my reach atm.