They may have gone up
Other option which will be only $250 is find a rear from an older Lux, the surfs generally ran 4.56 as did a few others. Look around and you will probably find one with an airlocker fitted for around $800.
The front at $429 is still cheap though if you really dont want to pull the gears yourself then even just taking the centre to the shop will save you money. If all you want to do is drive into a shop and drive out then yes expect 2k. However it seems here like most forums people realise doing things yourself will save you money and more money saved means more mods actually happen.
If it were me here is what I would do. Look around for a 2nd hand rear with 4.56 and locker $800. Buy the gears for the front $450. I would fit the rear myself simple swap in and swap out obviously give the bearings etc a quick check but thats it. Pull the front centre out and personally I would fit it myself however if you wanted to pay then $400 would cover it as its a 1-2hr job once the centre is removed.
So you are up for $800 + $450 + $400 = $1650 for a gear change with a rear locker. If the gear sets are selling for $430 new then you would get $250 for the front gear set and $350 easily for the rear centre complete that you removed from your truck. So take $1650 and remove the $600 you get back and you have a locked rear and regeared for $1000.
If it were me I as I said I would fit the gears myself and spend the money on an auto locker up front. So for $1200 I would have a regeared dual locked rig. In fairness you would probably need to buy the locker switches and compressor etc but that could be bought after a month or so if needed.
Thats just me but if there is one thing I have learned its that doing things yourself and looking for second hand bargains will allow you to get what you want to suit your budget. The above would cost me $1200 but most would think regeared and dual locked was going to cost them $1500- $2000 regear, $1600 rear locker install, $900 front locker install. A lot of people would look at it like that and say woah 4.5k of mods add it to the one day list
My old Lux stayed pretty much stock for quite some time as I always priced getting mods done. My old auto locka was the first real mod I did myself. From there I met Twisty and other mates, then body lifts, regears, suspension, engines etc all became affordable by using the above method. I have forums and people like Twisty and other mates to thank for it. Dont take my post to be having a shot at anyone its just that a few years ago a similiar post helped me start on my truck