you could probably try a perspex fabrication company in their cutoff bin(s)
i got about 40cm x 30cm x 1/2" polycarb sheey, 30cm of 3" OD tube and some plexi sheet for 15$ aus from one
the making of a res with the tube tho may be a problem, as imo sticking th e end of the tube onto the flat surface of the plexi sheet may not be enough to hold it on properly what with the stress from tubings etc...
ie:
if im not mistaken this is what you want to make right? if so anyone think using the standard solvent glue will hold this strong enough?