The only labor you should pay for is to have a shop assemble the front springs and shocks to the upper mounting plate which would probably be around $50-$60
Do the lift yourself- you'd be way happier knowing YOU did it, you'd learn a hell of a lot about your Jeep and you wouldn't be out $600+ when the shop probably doesn't even know KJs so they might screw stuff up (although they might since you said they're a 4x4 shop)
I promise you that you'll love to drive it that much more and be much happier after putting the lift on yourself than just picking it up from a shop and having to give them a whole bunch of money
I grin at my KJ (and talk to her sometimes too :emotions34
just because I know I put hard work, blood, sweat and (I wouldn't say tears but) a lot of anger into it
But it was all worth it in the end
The only way I'd fork out that money and take a gamble with someone handling my suspension would be if I had zero options left
No tools, no driveway/garage, no beer
Because those are all it takes to get it done