Keep in mind that these non-gigs are not all created equal. If you call someone for a $200 gig they can't play, they can't repay you with a $100 gig you can't play; they'd have to call you for two of those. Likewise if you call someone for a $200 gig with great musicians at a classy venue, they can't pay you back with a $200 gig with mediocre players at a dive. But this one's tricky: Having to turn down a better gig will make you feel worse than turning down a lesser one, even though the gig itself would be a nicer experience. Your feelings have value, too, and that raises a difficult question: Which offer creates a greater debt, and how can that be assigned a more realistic monetary figure?
The good news is that you can bypass monetary equivalents altogether: Your calls don't even have to be about "real" gigs! Just find a date where a player is booked (hint: website calendars are a great resource) and make the call. Until they figure out what you're doing, you'll be owed more gigs you can't play than you'll know what to do without.