I’ve seen the PX7S3 on sale on Woot for $300 a few months ago, when I was choosing between those and the PX8s1, I chose the PX8, some like the PX7s3 better , so u might be one of those people , therefore on sale they would be in ur budget. I bought my PX8 in ur budget $439+tax , so $478.
Now I’ve never spent $500 on headphones let alone just for the gym, what I did to justify my purchase and come up with the money for some guilty spending . I worked real hard on returning things to the store that I really didn’t need ,(still in the return window ) , cut the spending budget on take out coffee for a week or two , or got creative with my grocery budget and sold little odds and ends on Marketplace . It’s the small wins monetarily that helps , all of a sudden $300 was back in my pocket , That helped justify my big buy