First of all, thank you all for your messages and explanations.
After making a few verifications/tests, it appears that I don’t see much difference, if at all, at lower frequencies, between a 50Ω cable and a 75Ω one. Or it’s so small that it’s negligible.
I will invest in some higher end cables though, sometimes in the future.
For now I bought a few meters of RG58 coax, and made my own cables.
It’s probably good enough for most of the stuff I do and learn at this point.
I don’t do any RF stuff. Maybe I will in the future once I’ll get my chops up.