I know this is a core belief of yours, but I have never been able to accept it. It is not about what you can get away with, which is what you are implying. It is about how to build the best possible wheel. So just because you can have greater tension variation without it affecting wheel durability in a higher spoke count wheel doesn't justify building the wheel that way. Irrespective of spoke count the best wheel will always be with as perfectly matched spoke tensions as possible. I wouldn't accept variability in a purchased wheel just because it has a high spoke count. Why would I want to build one that way myself? And that means (for most mortals) using a tensiometer. Especially in a crossed lacing pattern tone is an unreliable measure of spoke tension (too many variables like spoke cross sectional area variation, crossing point, whether the crossed spokes contact each other or not, etc.). And doing it by the feel of spoke tightness or just by counting nipple turns is highly unreliable for the majority of people and cases.

Long story short, I think the $500 budget is reasonable for both components and proper tools. See places like the Bike Hub Store web site or BDOP's web site for the parts. Go with shallow to medium profile aluminum rims like Kinlin XR 200 or 270. Asian hubs. DT Revolution or Sapim Laser spokes. Say $60 for 44 spokes and nipples including spares, $100 for rims, $150 for hubs. That is only $310 plus maybe a little for shipping. Plenty left over for the tools. Getting under 1,500 grams (actually under 1,300 g if you want to) for that amount of money is no great trick. Easy-peasey.