Adam is right, it's not just the turbo kit you have to pay for. You need at least a big frount mounted intercooler, an upgraded clutch, piggyback electronics (VPC/GCC) or a different ECU, a large fuel system, NOS (if you will have a really big turbo), a boost controller, downpipe (not always included in the turbokit), bigger exhaust (go with the HKS Titanium, it can handle the biggest turbos), different cams, etc.
Sound Performance is developing an entry level turbokit that will cost about $2500-$3000 with the smallest turbo but you can always get this kit with a big turbo. I don't know if they will fit a RHD car though.
Also are you going to fit it yourself? If not labour will be a substantial amount of money especially if you go the different ECU way which you need to finetune.
Flavio