The cost of new wheels depends, largely, on what you use to build them. If you use higher end Shimano hubs, a quality Velocity or Mavic rim and good spokes, a build will cost you around $100 per wheel.

Be aware that 'quality' doesn't mean 'heavy'. A heavier rim is just heavier, it's not really stronger. I use Mavic XC717 rims on my mountain bikes which some of the lightest rims that Mavic makes. I jump them, I pound them, I beat them on rocks.

And 'good' spokes aren't just any old spokes that the shop happens to have in stock. If you want the strongest wheels possible, use DT Alpine III or Wheelsmith DH13. These are spokes for tandems and heavily loaded touring bikes. The spokes are more expensive but they are also stronger and more durable. I had a DT Alpine III spoked wheel that lasted up to over 10 years of hard off-road riding. I don't use anything else to build wheels with now.

I'd suggest Kool Stop Dual compound MTB pads over either black or salmon.