pass on the bags, especially if you have to c notch.. its not engenerrable in most staes now... and with the new aust wide code of practice about to come in soon all c noctch will be no more and air bags will be a 50 50 chance.

They are freakin tough on yes and no's of what you can and can't do. In the states they really don't give a ripped arse what you do and don't do at least where I live.

A kit for $2000 - $2500 installed is very cheap. Personally I cant see it being that price for a 1200.
Air bags in a 1200 arent bolt in.
The rear of a 1200 isnt that hard to bag using common setups, either modified leafspring pack ( not the best method) or 3 or 4 link style setups.
In the front there are more issues.
1200 strut towers dont leave much room for an airbag strut. There is no airbag strut on the market that is skinny enough to fit a 1200. This means alot of fab work is required. Thats means "Cost"
The easiest way to have air suspension in the front of a 1200, is with air cylinder struts. These take the place of the normal shock/strut/spring assembley. $300 each for the cheaper priced struts and still need to be made to suit a 1200 - the cost easily adds up. Only problem with cylinders is a harsh ride. This is due to the cylinders having no flex unlike a airbag which still acts like a spring. The only way to make the air cylinder ride a little less harsh, is to run acumulators for each cylinder ( Basically a tank that gives a bit more room for the air to compress when the wheel hits a bump )
You could run Hydraulics ( not legal in Australia) but it will give a harsh ride aswell)

There a few cars poping up on the net lately which are running a (Hydraulic x Airbag) setup. This setup is ideal for a 1200 front end, as it gives a normal airbag ride feel.
Its pitfalls are, it takes up lost of room, its more complex and it has many of the normal hydraulic problems like leaking seals etc.
This setup uses 2 hydraulic cylinders and 1 airbag for each corner of the car that it is used.
1 hydro cylinder replaces the shock in the standard strut. This strut is linked to the second strut in a push pull setup. And the airbag actuates on the second cylinder.
Basically the airbag expands and causes the second cylinder to compress and this transfer of hydraulic fluid causes the cylinder in the strut to expand and lift the supension of the vehicle.
All road bumps are transfered back through the cylinders to the airbag which compresses like a normal spring would occilate.
Lots of work, Lots more room used, Lots more money etc etc.

If you want a normal airbag ride feel in a 1200 you either have to modify the strut towers a lot and fit airbag struts or fit a complete double wishbone suspension to it.
The complete suspension swap is going to be less work to engineer in the long run but still a lot of work.

Or just run air cylinder struts and live with the harsh ride.

Either way the cost will add up.
Depending how low you want to go and what you want to drag, will determine how much extra work and cost will be involved.
At the end of the day, if you cant lay the car on the ground from front to back, whats the point of all the work and money?

You can go the cheapest route and buy airbagit.com/chassistech, but you will pay twice as much in the long ron when you have to replace many of the parts.