What is you price point and skill comfort level with building yourself? Do you have a schematic for your board?
You could compare it to schematics for boards with a meter bridge.
You can look for "VU Buffer kits" on the internet. Then decide where how in the signal chain you want to place the metering.
I'm no expert here, but I understand that you can't just stick a VU meter by itself into a circuit or signal chain without some kind of buffering, or the meter can introduce distortion into the circuit. JLM Audio in Australia and one or two Ebay sellers from China sell buffer kits.
There are also some Russian ebay sellers that have a VU buffer circuit that is contained almost all on one chip. Shipping may be better from Russia than from Asia/Oceania.
You obviously will also need VU meters. THere is a lot of information available about "True" VU meters, vs ammeters with VU scales. Probably you're OK either way though.
