Augs can actually be modified without stripping the gun to have a single fire mode. You just need to grind the plastic safety bar to catch the trigger on a half pull, then make a V notch in the bar so it will lock on the metal shim in that location. Takes about 30 mins to make the modification with a small V file and a scalpel. You take off the upper receiver, pull the trigger to dry fire a single shot and mark it on the trigger plate then release. This gives you the measurement for the amount of material to remove from the safety bar. You cut a chunk out of the upper side left of the bar the same depth as the measurement, put the bar back in and move it while pulling the trigger to find where the bar needs to sit in the hole. Then you mark the point where the metal retainer clips dent is sitting and file the V at that point on the safety bar. When you put the bar back in you will have a new locking point on the safety that only allows single fire, and you still have single and full auto in the original position.
The Aug is a nice gun if you spend time on them. Out of the box you get a reasonable gun that is really loud to use because of where the gearbox sits. A bit of time and some padding you can make them very quiet. The gun itself has a lot going for it, nice optic on the A1 and it comes with the gun (can't be removed). Good inner barrel length 509mm, Almost stock v3 gearbox. The only special bits are the airseal nozzle and a second set of contacts for full auto.
In terms of parts availability, nothing is really special with them. A new plastic body can be bought if needed, all of the body pins are available, even the ejection port covers arn't hard to find and they tend to be petty cheap. Gearbox wise you can buy a full aug box or a V3 and put the old airseal and contacts on it. It's not modified in a way that means it's a gun specific gearbox at all. New uppers are also available. And there is nothing to go wrong on the trigger as it's a plastic slider with a spring. All of the mechanical parts of the trigger are on the gearbox.
The main fault with the Aug is the noise, Your head is resting on the gearbox, the a1 style front grips are poor and some of the aftermarket magazines are poor feeders. Outside of that there a decent enough purchase, easy to strip and work on. It's 2 screws and the slackening of 1 bolt to have the whole gearbox and motor out. 1 bar to have the whole upper receiver off with the barrels and hop. If you had a full spare gearbox you could swap it out in 2 minutes.