We do things a little differently.  Our conversion kits use the factory 993 Twin Turbo rotor and hat.  Why?  Ever try changing rotors on the other "coleman" or "Racers Group" kits?  Either they use an after market rotor and gouge you after the fact (I paid $500 for replacement rotors from them), or they attach the 993tt rotor to an adapter plate with a bunch of fasteners. Here's their kit, if you are interested in it I'm happy to sell it to you.  I was getting 2-3 track events out of a set of rotors ad finally gave up and designed the Instant-G kit!

We don't like this.  In order to change this rotor you have to remove the 2 caliper bolts and slide it on.  It's a light press fit onto the hubs we have specially machined.

Here's the hub.  It takes standard 911 bearings but it's not a 911 part number!
 
 

On the car.

Pricing:  $1599 includes 2 calipers, 2 adapters, 4 bolts, hubs, bearings, and a pair of factory rotors.  You supply lines and pads.
Pricing on the rear is $1699.  So you are looking at $3300 plus pads for 911 through 89.  Hubs, bearings and front brackets with hardware are $695

Is it the cheapest?  No way.

Rear setups:  We recommend 28 mm 930 rear rotors with 944turbo/C2 front calipers.  They can be machined for adapters.  I have 993tt brakes on the back of the Tealamonster and for my money it's overkill.

If you insist we can make a set up for you.  993tt rear calipers, $400 in machining, $250 in adapters, $750 in calipers, $300 in rotors. $1699.  Again, not cheap and more than you need on a 2500 lb car.