Who knows, the price goes up constantly. Check ebay for closed auctions with recent dates. Sorry I can't give you a firm, fair trade price.
I haven't seen one at a gun show in a couple of years. At that time we thought it was outrageous for one in really bad condition with an asking price of $150. Suprize, it sold quickly. I guess the guy jumped at it because he realized he may not see another.
Back in the mid 1990s I needed a gold box. I found a gold and a red box together on a table, being sold by a book vendor, no less. He wanted $25 each for them, but sold me both for $40!
Those days are long gone.
A while back we had an exchage here on the forum where someone had seen a red box selling for $250 and we thought it was terrible. Its just progress. Fuel is $4 a gallon, too.
Years ago, Ray Brazile had an 8 3/4" RM box on his table. I wanted it badly. I couldn't bring myself to spend the money. Within a few minutes, it was gone.
Prices are set by supply and demand. A lot of people want the boxes and there aren't many for sale.
Just the addition of a box to a gun takes the value up significantly. Much more than the cost of just a box alone. Over the weekend I saw a K22 Outdoorsman in a red box with an asking price of $1595. I wasn't shocked, but last year that would have been a joke.