You can make one. It's basically a "sample and hold" circuit. The trigger pulses are very narrow and far apart. A regular meter can't register that. But the DVA is merely:
A pair of wire leads, one for the trigger source you want to measure and the other goes to ground, bat - or engine block.
A 600v or so 1 amp or so, diode with the Anode lead (the end with the arrow part on the diode symbol, not the bar at the point of the arrow which is the cathode) connected to the positive DVA (you are making) lead.....that connects to the trigger signal/voltage.
Attach a .47 microfarad 600 v paper/paper-plastic capacitor lead to the bar end of the diode (cathode) along with one end of a 1/2 watt or so carbon resistor of 1 meg ohm give or take. The other lead of both the cap and res tie to your ground lead. The components aren't all that critical. You can put 2ea 1 microfarad 400v caps in series with each other....capacitor value is halved in series and voltage breakdown is doubled. Resistor.....just get close.
Set your Digital voltmeter on the 400 or so DC volt scale. The red lead of the meter goes to the connection of the diode cathode, cap. and resistor junction and the black lead on any ground mentioned including the other (lower) end of the cap or resistor.
Run your engine at idle or the specified rpm in the manual (don't forget to put the water and muffs on) and give it time to charge up the cap....a few seconds. Correct voltage value is in the manual. Will be several hundred volts. I don't have mine any longer or I'd tell you what the number is. If you need a quick manual you can rent online time from Seloc manuals......check out the icon at the upper right of this page.
Obviously keep your fingers off the hot side of the cap. Enough stored energy there to give you a good whack! If you switch from one cylinder to another in measuring, after you disconnect from the trigger source, give the cap time for the "bleeder resistor" to discharge it and let it recharge to the new level.
Radio shack or a tv repair shop will have your parts.
Good luck,
Mark