Where can I get an extra vacuum resevoir?

[WSLN 6]

I want to help my vacuum brakes out a bit at the track by adding an external vacuum resevoir.
Can I just use one of those vacuum balls like on our cars, or is there a better solution?
I don't feel like paying $50 US for a resevoir (Which is crazy....), I would rather look for a likely candidate from a junkyard.
Would Imjust T into the line going to the brake booster, or does it matter?

 

[WSLN 6]

ttt

 

[REDS HOT AIR]

call summit racing and get one of their brand ones it will be cheaper than you think.

from what others say on here it works fine t'ing into the pcv hose