I can’t believe this hasnt been blasted with posts. The emissar D1S, Lumintop ODL20C, Astrolux FT02, KD c8.2 (xhp35 HI emitter). All have throw exceeding your 500m requirement with decent spill and are all under $75. There are many others as well.
Early testing of the Astrolux latest FT03 show great potential but I have personal concerns about astrolux quality and lack of warranty support.
If you really need 500m throw then you would need a headlamp with a large reflector or maybe a large zoomie. And if you need to see something 500 hundred meters away you probably need a light that is rated to far more than 500 meters. I have a bunch of headlamps and the throwiest I got is the nicron h30. I measured 22KCd (~300m) with the stock XML LED. Ugly UI but it’s very easy to do an emitter swap so you can swap in a xpl-hi, sst-20 or White flat to get more throw. Difinitely won’t reach 500 meters though. The 34mm nitecore diffuser fits very well if you need it to be floody. Throw and flood in the same headlamp I only know of the fenix hp30r or those expensive caving headlamps (Scurion, Phaeton, El Speleo etc.). Again, I doubt they they reach 500m. If I had to guess probably up to 200 meters.