Excellent, now we're talking.
Thanks for all your replies. I feel I should clarify some things.. First, I am not a working DMT, though I already mentioned this. I did my DMT while traveling in SE Asia, so buying gear was out of the question as I didn't have loads of money. I'll probably end up working as a freelance instructor, so there will be no requirement to use shop gear. I am currently in Europe saving up money for equipment & IDC, so buying used gear is out of the question for the time being as there are not many divers here.
Where I did my DMT, most other DMTs used shop gear as well. They were mostly in the same boat as me. Hell, quite a few of the guys who did their IDC while I was there used shop gear.
Decided against air trim; like someone said, students won't be using it. I don't want integrated weights for the same reason. And yeah, I do intend to get an SMB, knife, etc as well. But I can get those things locally. From what people have told me it is quite a bit cheaper to buy the "big" things online. Estimate $1500 for reg, BC & computer locally. Might find used gear but I don't want to bet on that, only to arrive and be forced to buy expensive new gear. I'd rather save $500 and hope the internet BC fits nicely.
I was thinking I'd just get a compass to mount on the computer wrist band. A friend got one and it was quite reliable, and a bargain.
Bubbletrubble:
I would try to buy middle-of-the-line, robust, easy-to-service used gear.
That is what I was thinking with the items I listed. Mares can be serviced most everywhere, and that BCD is meant to be quite robust. Also, the big pockets.. I will be diving in tropical waters, so I'll wear a short wetsuit at most, ie no thigh pockets.
The reg is the part I am least certain about. The Aeris one is marketed as robust, and in the package it comes with a Mares SPG & octo, all of which made me feel a bit more comfortable with it.
I can always get a Gekko for a computer, like someone also mentioned, but that will cost $300-350 locally, maybe 50-70 less used. People seem to like the Aeris on these forums, and it is a steal at $150. There's also the Mares M2@$165, which is also a nitrox comp. After reading some reviews I'm more inclined towards that one now.
Naturally I do not rely solely on an Internet forum to find out what I ought to do. I've asked the people I know, done a bit of research and will continue to do so, and I'll probably check in with a LDS if I can find one.
Thanks again for your replies. Unfortunately, more insight has left me with more confusion. It is clear that I have a lot more finding out to do before I take action.