So I was getting tired of mixing sugar and yeast every few weeks and having inconsistent and low Co2 in my 10 gallon tank. I wanted the convenience of pressurized, but just didn't have the room for even a 5lbs co2 tank and regulator, but even if I did I didn't want the eyesore of all this large equipment next to my small little aquarium. I was looking for something to sit next to the tank that wasn't too intrusive and looked nice.
I found this regulator for $100 at Austin homebrew. It has an adjustable pressure output and gage.
The regulator accepts threaded disposable cartridges like the ones below. I get them in two packs at my local Sportsmart for $10
The Co2 Cartridge (88gram):
There is also many other sizes of tanks available that can be used
The setup is very similar to the ADA style regulator and it is my belief that they come from the same manufacturer
A pic of the regulator:

One thing I don't like about the ADA version is that there is no solenoid valve. I figure not having a solenoid valve I would be wasting a lot of Co2 at night and it didn't have the luxury of lots of co2 reserve with the smaller canisters so I went about adding a solenoid, but not just any solenoid. I wanted something that was going to blend in with the regulator and not be too bulky. I found this sub-miniature regulator from Asco scientific. It was about $50
The valve runs off of 24v DC, 12vDC version is also available, but there was no 110/120 V AC version so a transformer was needed to adapt it. I had a 24v dc transformer laying around from a broken appliance so I went for that one.
I also got these small clippard parts through Rex Grigg here on the planted tank- Thanks Rex!
-4CQF 1/4" NPT to #10/32 bushing
-11999-NP male 10-32 connector

-15002-2-NP "L" fittting

-MNV-4K1 Needle Valve
So I put it all together and this is what I got:
The whole assembly hangs from a custom hanger I made out of a piece of plastic from Tap plastics. I also used a Lee's heater holder to secure the bottom of the CO2 tank to the side of the aquarium. It is very secure.
I have had the system running since the beginning of the year without the solenoid at about one bubble a second. I have a Barr style venturi reactor so I can count the bubbles from there. I was using a diffuser with built in bubble counter also, but I liked the reactor better so went back to that. At this bubble rate I get about 4 weeks on a 95g cartridge. Now that I have added the solenoid I think I can double that.
When a tank runs out end of tank dumb is virtually non-existent. There is a slight 2 psi jump on the gage that usually tells me that in the next 24hrs. it will run out. I like to always keep extra cannisters on hand, but they are everywhere- Walmart, Kmart, Sportmart, Hardware store, Cycling shop etc.. so getting one quickly is usually easy. Swapping them out is as easy as unscrewing the old one and screwing in a new one. Takes less then a minute.
Total cost of the system was around $180-200 give or take. Much less than the ADA version plus it has the functionality of the solenoid and larger Co2 capacity. I realize that this is not the bang for your buck that you'd get off of a 5lb tank and traditional regulator, but for me it was worth the price not to have this large tank sitting on the floor next to my aquarium.
If anyone has any questions let me know.
Jeff