Would Like A Retail Estimate On A 8 Reale

I'd start at $100 and probably pass if he wouldn't take $125.

NGC World Coin has VG at $175, which would represent a higher retail price. I would agree with above that $125 would be the max because you really like the coin. As a commodity, might want to keep it a tad under $100 if you can. Is an extra $25-30 worth the sentimentals of this one in particular, the difference between having and not, is up to you :)

The homeland Spain bust 8 Reales are of course much scarcer than your typical Mexico/Potosi/Lima colonial 8R... and narrowing further, the most common Charles III dates are less frequent than the most common Charles IIII or Ferdinand VII issues. Note however that this piece is about as worn for the type as you could find. In all seriousness, if the Euros were into "lowball registry" style sets like we silly Americanos sometimes assemble, this would be a prime candidate (the criteria being heavy wear but no damage).

Anyway, as I said, they are scarcer than typical colonial mint issues... hence the less frequent appearance on ebay and elsewhere. Do note that interest is more focused in Spain proper - and perhaps to some extent in Latin America - moreso than here in the States... We are more interested in the Central/South Amer. mints whose output was what circulated in the Colonies/early U.S. (except of course for the Spain "pistareen" style shield 2R).

It is probably worth what you paid... perhaps a bit more could be squeezed out because as a type they are rather scarce. Truthfully, if you ever delved more seriously into reales coinage or more particularly the issues of peninsular Spain, it would be a piece to upgrade.