I think I found a way to get the prints in Nylon PA12 quite cheap. The initial price of each parts was about 15 euro (taxes not included) each or 13 each if there is more parts.
I read somewhere that the print was actually priced based on the volume taken by the print. And I know that MJF doesn't require any support. What about putting my parts in a box with holes so I can get all the parts together in one print. I created a box in Tinkercad with holes, added the parts inside, making sure than non is touching the box or another parts, and let's see.

Bingo, it seems that it works. I added a small recess of .25 mm on the top of the box to facilitate its opening, and resubmitted for quotation. The price is around 46 euros before taxes and shipment (was more than 120 before I found this trick, and added some parts inside the box with a marginal raise of the price).


Order is done. Included 6 idle gears, 4 bumper reinforcements, 2 sway bars links for Turbo Optima (I have a sway bar that I could eventually mount on the Javelin), and two front led supports, Shipment of the parts will happen by mid October.
Let's see how it goes, I will let you know...
edit: by curiosity, added all the files separately without the box : 182€ down to 46 before taxes, thanks to the box