Ok, so my prices are somewhat irrelevant, but I paid £10 (~$15) per wheel last time I had any mounted for me (remove old, new valve, mount new and balance).
Check disc runout? I'm assuming you mean brake disc. Why pay an hours' labour for that?
Put the bike on the stand, support it so the wheel is off the ground and turn it slowly while peering into the brake caliper - look between the pad and disc for variations in the clearance - if you want to get all posh you could stick a feeler guage in there at the highest and lowest point, subtract the thinner from the thicker to get the runout figure.
Balancing - I'm a bit 'agricultural' when it comes to this... I don't bother to have car tyres balanced at all any more and haven't noticed a difference - yet. Maybe I would notice on something smaller than a Land Rover :laugh On a bike wheel I'd do now what I've always done - push the brake pads back into the caliper a little to remove resistance from the brakes, give the wheel a few spins and if it always stops in the same place put a smallish weight at the top - repeat until it stops at random places and it'll be balanced enough. Fine, the machines will balance a wheel to within a gram these days, but take the wheel off the machine and put it back on and you'll get a different figure in a different place (I used to do it for a living, so I have tried it).
Oh, if you haven't got any already find yourself a set of rim protectors to use with the tyre levers - with aluminium wheels it's easy to gouge a chunk out of the rim.
