Well how much VRAM do you feel you need for your projects? Because there's a lot of 16 GB cards out there that are still perfectly serviceable for that.
Vega Frontier Editions (16 GB HBM2) are going for around $600-700 on eBay and Craigslist, also Facebook Marketplace in some areas.
Radeon VIIs (16 GB HBM2) are going for around $650-1000 on the same platforms.
You can easily put two of those into a machine and have a pretty impressive deep learning rig.
Vega Frontier Editions (16 GB HBM2) are going for around $600-700 on eBay and Craigslist, also Facebook Marketplace in some areas.
Radeon VIIs (16 GB HBM2) are going for around $650-1000 on the same platforms.
You can easily put two of those into a machine and have a pretty impressive deep learning rig.