I did the swap on mine. I can't speak to the price of having a shop do all the work as I am a welder and fabricator and old school car guy so I did all of the work myself. I converted mine because its nice to have the option when needed. I don't do a lot of off roading and what I do doesn't really require the locker, just a good set of tires and decent driving skills (which is an argument for another time).
So, I want to approach this from two different views.
First, If you don't do any real hard core off-roading and you have a winch then you probably don't need the locker. However you need to weigh how much you use your winch each time you go riding and take that into consideration on buying the locker because the locker can help to keep you out of those situations where you might have to use the winch. Also, the locker tends to build false confidence when you go off roading which ends up getting you into situations that you might not have gotten into without out it, so it will eventually not be enough anyway.
Since you said you do a lot of snow wheeling I can't really recommend the full locker but would suggest something like a posi-traction or something else that would be a little more friendly on frozen black top.
As far as doing the actual work. Its really easy to do the swap. The hardest part beyond doing the welding is drilling and tapping the holes. If your not careful when doing the welding you will harden the steel and make it almost impossible to drill for the tap. Also, keep in mind that getting the 3rd member to sit flush against the housing requires a lot of added metal and getting that ground flat is a lot of work. Its easy if you have a endmill and can set it up for a machine to do the work. However, if you do it by hand - which I have seen done - you need to make sure the 3rd member is sitting square and flush with the axle tubes and isn't in at an angle or it will cause other issues all together. I haven't seen anyone warp a housing from welding it but I could see where it might happen and I don't think that can be fixed without some serious work.
Plus, when you do the locker swap you need to rebuild the entire 3rd member and axle bearings. I have yet to figure out why in the world someone would put in a used 3rd member without replacing all of the bearings. Which leads to the second main problem everyone runs into, the gearing in the locker 3rd member doesn't match whats in their rig. So you end up having to swap the pinion and ring gear from the old unit to the new unit.
All of these hidden rebuilds start to add up quick!. So that 500 dollar (I don't care what these well wishers want to say your not going to buy a used stock Toyota e-locker 3rd member on Ebay for less than 500 dollars) e-locker install turns into a 1500 dollar install.
So the ultimate question is, Would I do it again? Probably not! If I had to do it all over again I would go with a Air Locker from ARB because if you ever decide to install a font locker all of the supporting equipment is already there and the ultimate price difference between a factory conversion in the rear - even with a full self install - and the ARB isn't noticeable between the two. Especially once you take into consideration that you should rebuild the used e-locker 3rd member just like you would have to rebuild yours with the ARB install anyway.
