Justin,
I would really consider used. You can pick up a great pair of headphones for a fraction of the original cost. Because these are high-ticket items, most buyers tend to treat them very well. Many of the headphones you see in my photos I've purchased used, including in 'broken condition. I've also found most people who spend this kind of money don't seem to be mechanically inclined to fix anything
I wouldn't go the eBay route. Try the buy/sell/trade section head-fi or usaudiomart
I'd look at entry-level planar magnetic headphones from Hifiman, ZMF (a local Chicago company), and Audeze.
good example - Local Illinois sale
https://www.usaudiomart.com/details/650024132-audeze-lcd-2/ 60% off a very nice pair of headphones you will be happy with. Is there better, of course, but that's like asking for a bigger motor :>
As for an amp, I would recommend an integrated dac/amp you can grow with. Schiit's are good (Asagard 3 or higher) If you want something permanently connected to your computer. If you want something portable, you can look at something like an ifi at
https://www.amazon.com/dp/B0CCC6DBPS/ , or a Chord Mojo 2, which you should also find used. I have an old Chord Mojo 1 which you could convince me to part with
I've gone to the extreme on this stuff. The tube amp you see in the photos is an Auris Audio Headonia 2A3, driven by a Chord Dave DAC. Can I hear the difference? I think I can, but I also intellectually know diminishing returns on my investments kicked in a long time ago.