Thank you very much. I’ve contemplated that option, but there’s two drawbacks:
1- I live in Spain. 2nd hand PCs are not as cheap as in the US or UK and intl. shipping rates for a desktop would be expensive.
2- Most outdated PCs in the second hand market are Pentium-D types or similar, which use a huge amount of power. Laptops, OTOH, don’t have SATA ports. My current USB solution has given me some file corruption problems under heavy use already.