I've been reading these forums for a while now but I made an account so I could reply to your thread.
I have a mid-2012 mbp retina, and somewhere around 2016/17 I had the logic board die on mine. I was in a very similar position to the one you describe - $500+ to repair a computer worth roughly that (give or take), or drop $2k+ to replace it? The second option wasn't really an option at the time due to being a student with a low-paying job, so I went with the repair. 4+ years later and I'm typing this post on the same computer, so I'm quite happy with the decision I made. I've also been fortunate in that it's the only repair this machine has required in the almost 10 years that I've had it now. Now, that said, I've recently started to see a bit of odd behaviour out of the computer that reminds me a bit of the first time it happened (hdmi and usb ports on the right side cause some weird stuff to happen sometimes), so there's a chance it could be on its way out again, but even if it goes soon the repair still feels like it was decent value to me, and besides, I now have a new 16" MBP coming to replace it, so it lasted me to pretty much exactly where I needed it to.
Obviously there's no way to guarantee you'll have a similar experience, but if you weren't planning to upgrade your machine for a few years anyway then the repair might be a good shorter term solution for you too.
I hope this was useful to you in some way!