Build the garage yourself or not? What is cheaper?

Hi, currently we are also working on the topic of the garage as part of the exterior design.

My wife’s uncle, a trained bricklayer, would help us build the garage ourselves.
Our house is made of 36.5 cm Ytong blocks on the outside.
We wanted to build the garage with Ytong as well.
A 24 cm block is planned here.

Size 3.62 m x 9.50 m x approx. 255-270 cm high, flat roof with slope to the back.

I already calculated the amount of blocks and would come to a price of just under €2000 for the blocks alone.
Keep in mind this is the average price according to the internet, for one block (so no bulk discount or anything).

Of course, I have no idea what the large sectional door costs, the roof, the ring foundation, etc.

We wanted to place the garage quasi as a U directly adjacent to the house to save space on one side.

We received offers from IMM garages, timber frame construction for €12,600 with electronic door, one window and another door.
Without floor slab and plaster.

Then from Fink garages, also wood for €15,000, primed without plaster and floor slab.

And then one in some kind of steel construction, from Exclusiv garages for €8,750, 3.50 m x 9.00 m
But you don’t read much good about that.

Do you think it’s better and cheaper to build it ourselves with masonry?

Thanks in advance.

If I forgot any information, sorry, ask me and I will try to answer.

You yourself come to about 10,000

Do you think you get better and cheaper results if you build it yourself?

If you do everything yourself, you should stay under €10,000. Foundations, floor slab, covering, plaster, electrical work, etc. are also added on top with each of the offers.

Electrical work was partially already done, but doesn't cost much, just a few cables, plugs, switches, and lamps. Neighbors are electricians and would also help with that.

If you have one, do it yourself, it's usually cheaper if he knows what he's doing

Length 9.5 m ... is it standing on the boundary? Then that could be too long.