For guilt-free arts files (art and photos), whether you’ve gotten digital files of my works from me or someone else …
Use the steps in the Proxri Deal to determine a reasonable expected minimum proxri for a period of time. Then you don’t have to worry. Of course you can add to your minimum later if needed.
Suggestion: For personal use of arts files (as opposed to business use), becoming a patron of mine on Patreon for $1/month might be a good starting point. Of course, everyone’s situation is different.