I recently got my Karate Monkey soda-blasted and powder-coated in Upper Hutt.
I was very impressed with the finish and friendliness of the folks up there.
You want to coordinate it so that the frame isn’t sitting around after being blasted for too long. I was very pleased with the result which was at least as good as the previous place I went to, and substantially cheaper.
Powder coating will not get the kind of finish that you would get from high-end spray painting, but there is no comparison with the cost. I think it’s a pretty good compromise.