3D Printing of 4 items from .STL files in black <200mm max len

I have 2 .STL files that I need to have printed, I need 2 prints of each, so 4 items in total, the max length is <200mm

The items are vents for a car (windscreen demisting) colour is black, any finish (gloss. matt, texture) is ok.
The vents will need to cope with warm (not hot) air, please recommend a suitable (low cost) print material.

If successful, I will need to see a small sample your print output so I can see that the colour and texture is suitable.
I will then ask you to print and ship the 4 vents.

The budget below does not include shipping, I will cover shipping costs with a separate payment.

I am not in a hurry for this, If I could have the items in 2-3 weeks that would be fine.

Steve
I am based in London SW19