Ok you asked for it.
Ok I did some looking around online and found a couple options for gauges I found liquid filled that are not all that expensive but I have no experience with their exact accuracy.
Shoping list:
1) "6" vaccum gauges
2) "6" Brass airline valves for fish tanks
3) "6" pieces of 1/4" Vynal tubing 2'-3' each for (Min 12' - Max 18')
4) "6" pieces of automotive vaccum line 10"-18" each for (Min 60" - Max 108")
5) some sort of mounting material? whatever you have laying around will work fine then you have to figure out how to mount each gauge as to be able to see all of them together at the same time and easily determine what cylinder each gauge will associate too.
Here are some links, remember you need 6 of each item
http://store.waterpumpsupply.com/2lifiststcog.html $10.00 each
A little better looking but cost is higher.
http://www.jegs.com/p/JEGS/JEGS-Liquid-Filled-Vacuum-Gauges/756008/10002/-1 $18.99 - $19.99 each.
One from holley carbs,
http://www.holley.com/26-501.asp$32.95 each
Here is a nice one but again on the pricier side. $39.05
http://www.grainger.com/Grainger/SPAN-Vacuum-Gauge-5ULR0Here is a model that is digital and VERY pricey but they would make a setup that MANY other Valk owners would be jealous of.
http://www.omega.com/ppt/pptsc.asp?ref=DVG-64&ttID=DVG-64&Nav= $160.00 each WOW!!
Then here is what I found from Ricky-D's vaccum gauge buildup. for $3.40 plus shipping.
http://cgi.ebay.com/NOSHOK-2-Dial-1-4-NPT-30-inHg-Vacuum-Gauge-NIB-/330357346654?pt=LH_DefaultDomain_0&hash=item4cead5115eDon't get me wrong Dags setup is really nice but I am just too poor to spend that kinda money normally, Mine works just fine so far.
One last thing here is the link for the Fish Tank brass air supply control valves I used on mine.
http://www.aquacave.com/detail.aspx?ID=217I hope this helps you and maybe someone else also.