This is a question of economics and the aplication of statistics.

I have some almonds trees and I have done some research for you.

There are 2 options.

Send your almonds to a cooperative or crack them yourself.

At the cooperative (in an article on the internet) the current price is
60 cents per kilo for almonds in their shells.

According to my measurements 1 kilo of almonds with shells results in about 132 grams of shelled almonds.

That would theoretically give you the price of 7.57 euros  per kilo of shelled almonds at the cooperative.

I spent 18 minutes 12 seconds cracking almond nuts which resulted in 208 grams of nuts.

That is 1 gram every 5.25 seconds.

At that rate a human can shell a kilo in 87.5 minutes.

By the way the cracking technique I used is to use a small hammer on a concrete floor.
First smash all the almonds on their sides with the hammer then later pick the almond nuts out of the debris.

The other important factor is the price of Almonds in the shops.

On the Mercadona website a kilo of raw almond nuts is 14 euros per kilo.

If you were paying yourself to crack the Almonds your earnings would be:

At supermarket prices
16 cents per minute or 9.60 euros per hour.

At cooperative prices
8.6 cents per minute or 5.15 euros per hour.

CONCLUSION:

With 40 almond trees it would be best to pick and crack the nuts yourself.
Almonds are very nuitritious.
Have you tried heating them up in a frying pan with a tiny bit of oil and  sprinkle of salt?
They are absolutly amazing.

Get a Chicken Korma recipe which uses almonds.

There is an interesting Andalucian cold soup recipe which is "Ajo Blanco".
It uses ground almonds and broad bean flour.
If it is made right it is really good.