My recommendation in your budget, having someone else build them. Shimano XT hubs or Ultegra, Velocity Aileron rims and R28/F28 or R32/F28 butted spokes. Should get you in under budget, will be lighter and will last. Personally I think at their price range XT or Ultegra hubs, and both come in your spec, can't be beat. They will spin smooth, quick and last a long time with basic maintenance. Another one I've built and been happy with was using a Sun Inferno rim which was also fairly light with a good width and has held up well. They started as MTB rims but come in a 19 and 21mm widths for gravel now but are sturdy.