Contrary to popular belief, it is possible to use a needle valve and pressure guage to provide a regulated DIY CO2 system. I have been using one for some time with great success.
I use this this hardware, but I use yeast/sugar for the CO2 production rather than the acid+bicarb they use.
I purchased mine from Ebay, search for Complete DIY CO2 System to check it out.
As long as you use a yeast/sugar mix that isn't excessive for the regulated BPS you require you shouldn't see the system pressure rise much above 1-1.5 Bar over the course of the mixture's active life.
However I also take the precaution of using a joiner in the CO2 tubing that doesn't have lock nuts and is therefore a weak spot that will pop long before the bottles would blow.
It has the added benefit that even after the yeast mixture has started to slow down, the system will continue to supply CO2 from the store in the bottle. I also find that my flo nano diffuser is much more efficient at the higher pressure.
Since I have been using this system I have had an easy to regulate, steady CO2 flow and I have to replace my CO2 mix less frequently.
I'm currently using this on a 200L heavily planted tank, and I'm maintaining a CO2 concentration of around 50ppm.
I've read a lot of threads advising against this, but I'd have to say that as long as you take the correct precautions you are no more likely to encounter problems than you might with any other setup.
This is a picture of my tank from a few days ago.