Beyond a Raspberry Pi 500 …

If you want to try to get better results than I was able to produce, consider using a Raspberry Pi 5 with the maximum RAM configuration (16GB), an add-on board for SSD storage and a case with integrated fan. A

As the market for memory has been wrecked by the AI industry, this will push the project sadly beyond the line where I would consider it 'low-cost', landing somewhere up to €/$400.

It might be a better idea to look out for cheap used mini PCs or just to work with hardware you already have.