[fortgreg]

I'm sure there are some knowlegable Fox guys on here, but with your broad description and no picture, it is impossible to determine an exact value. A 20ga Fox is a very desireable gun, and it was offered in many different grades. Condition is what determines the value on any collector gun, and peoples opinion on condition vary like the weather. A picture is worth a thousand words.

 

[fortgreg]

No problem. I struggle with pics too! Is the gun missing the whole stock, or just the buttplate? If the gun shop offered you $500 for it with a questionable stock, you may have a higher grade gun.