Not so fast, Jkal. The prices of all the Pagodas have been rising. Yes, the 280 is, to the market, more desirable and thus is priced as such. Despite the rarity (and opine of thelews) the comparative rarity of the 250SL doesn't translate to the marketplace. Just a few years ago, the record price for a Pagoda was a 230SL...
One thing is pretty certain, and this is for all cars in the collectible or classic category. Unrestored and original examples are commanding higher prices than ever; well done restorations behind that. What isn't appreciated (as evidenced in the value category) are cars that have been toyed with and we all know what that means.