Secondary regulators

Has anyone built a system using lower cost modular regulators (typically used in FRL air compressor systems)?
They seem like they'd work just fine... they have 1/4" thread varieties... have lots of selection and are typically fairly inexpensive ~$30 each...
I'm trying to figure out what I want to do in regards to regulators and this seems like a possible solution using a primary with a few of these as secondary...

I have a secondary split off my mainline so i can force carb one keg and keep all the others at dispensing pressure. are you just trying to hook up multiple kegs, dispense at different pressures, or carb some and dispense others?

I understand the purpose for secondaries... I plan to carb/serve at same pressure... but plan to have a bottle of water (30PSI) plus likely a hefe (20) and something else at the typical 10-12...
I'm not sure what route I want to go yet... dual primary regulators... or a single regulator at say 30PSI with a couple secondary regulators...

Specifically, I was asking about sources for cheap secondary regulators... and alternatives to what most of the brew sites offer...

I always check for closing bars or restaurants. It's usually real cheap that way. craigslist and ebay have that sort of stuff occasionally. My neighbor works for pepsi and brings me anything he takes out of a bar or restaurant so i got mine for free but if you have a pepsi or coke distributor around you check with them because of lot of that stuff just gets thrown in the garbage anyhow.

sorry i didn't understand your question in the first post