Part

Cost

Place bought

This is not a complete list    
1" inch Ball Valve ~12 Home Depot
7' 4" sch 40 Had had
10' 2" sch 40 ~5 HD
Hose ends 2.49 HD, for pigtail
tee 3/4" 1.45 HD
3/4" galv. bushing 1.19 HD
1/4" ball valve 4.99 HD, for comp hookup
1" tee 1.63 HD
1" coupler m-m 2x 1.27 2x HD
1"-3/4" bushing .97 HD
3/4"-1/4" galv nipple .90 HD
PVC Primer 1.97 HD
1/4" compressor coupling f-f 2.84 HD
2"x10' schedule 40 4.99 HD
4" PVC bushing (2x) 9.98 HD
4" female clean out 2.97? HD
4" female clean out cap 2.09 HD
pressure guage 7.34 Napa Auto Parts
4" coupler   Had(made from flared 4")

Piston Parts:

   
3" pipe 4" Had
4" sewer pipe 4" Had
sheet metal 1sq ft   Had
rubber stobber 4.00 HD
more...