There are definitely areas we cans save $ on building our planes, but this wouldn't be one that I would choose. Brakes are one of the things I want to work properly with out any doubts. You don't want you brakes to fail at an inopportune moment, especially if the third wheel happens to be at the back of your plane.

Aircraft Spruce has a quart of Philips brand 5606 for less than $7. That should be enough to do your entire brake system. It's not worth the $4 you MIGHT save here.