I think we can all agree that 'value' is based not only on condition but overall supply and demand. As noted by several, .40S&W is no longer en vogue (was it ever? jk) and demand for the caliber is low which is a factor to consider. I don't dare wonder what the a P226 in .357 Sig would sell for today, or any of the other uncommon calibers on other pistols, eg 10mm.
In any case, the OP is looking for a rough value as part of a package deal, not necessarily that it would be sold. Stainless frames are no longer being produced (at the moment) but there are a number of later model stainless variants on the used market that were produced in much higher numbers than this 'original P226R-Stainless.' Is that worth anything? Well consumer decides.