I am building a commuter bicycle with mechanic disc brakes.
So far I bought a custom steel frame. I want simple commuter not expensive but good quality. There are too many robberies of bikes so don't want get bull-eye in the bike.
The first part I want to buy is the hub, so I wanted to get a tourney tx but I found that they appear to be discontinued. The tourney tx is not listed in the homepage of shimano anymore.
So I searched and I am looking to get acera.
However In the stores of my city they told me the hub they used to sell is the m4050 and the price was good between 30 to 40 dollars, but it has been one month and there is no new supply.
And the hubs are online but the price is around 100 dollars....
There is something that I don't know?...shimano is going to replace tourney tx, acera and alivio?...there is another brand?....the 3x9 is discontinued?...

Deore m525 hubs can be had for $30 if you shop around, and they are the bombproof core of many better quality OEM wheelsets. They are heavy, but they work great, and are nearly indestructible. Years down the road the original grease will still look new.

Are you joking? A custom steel frame with Tourney hubs?

By custom I mean hand made for my size....and I asked for disc brakes...so they did not included how secure v brakes.
And the frame is basically a classic touring.
I asked around and the people told me that the tourney tx is very good and resistant...I want a hard working commuter not a machine to do races.

The m525 can use the groupset m3050? they could be solution I am looking.

But the question remains why is so difficult to find the hubs m3050 and m4050?

Because few people would ever buy an Acera hub to build a wheel on. Why would you, when Deore hubs are already cheap enough?

Deore m525 hubs take six bolt rotors and are 8,9,10 speed compatible. So, yes.

I run the XT 756 rear hub and an Alfine dyno hub up front. Lots of sources, I use universalcycles.com

Agreed. The lower end Shimano components are frequently found on complete bikes because that involves mass production and so tiny difference in price add up to large differences in revenue, but the margins on those parts are small enough that most businesses wouldn't carry them for retail sale.

For instance, one large U.S. retailer where I shop has the M4050 Alivio front hub for $20 and the M615 Deore front hub for $24 and the M525 Deore front hub for $21. I would guess that if they offered an Acera hub it likely would be around $18-$19. There just isn't much cost savings for the buyer -- a dollar or two on a wheel that will cost around $60-$75. I'm surprised they even bother to sell the Alivio hub.

There is almost no benefit to the lower end hubs. The initial cost is very slightly lower. The more expensive hubs are at least as durable and probably slightly more so. Addressing your specific concern, I seriously doubt that potential thieves make any distinction between an Acera hub and even Deore XT hubs.

You don't mention where you are, but since you referenced a price in dollars I'm guessing that you're in the North American market. If so, check out this link for a good selection of hubs:

https://www.universalcycles.com/shop...p?category=740