That is not unreasonably more expensive. Besides just higher profit margins, there are a lot of other factors going into the price besides "cost of goods".
Chief among these factors is the higher and more specialized/qualified labor costs, leading to higher construction quality and durability. There is also field testing - more of which costs much more. The same argument applies to the individual raw material suppliers - there are premium and budget qualities and suppliers for most materials. This recursively adds up to the final price.
The specifications you copied do not say anything about the quality of the outer fabric (how breathable and water proof), the kind of stitching, zippers, additional padding at the chest, etc.
This is similar to how a similarly specced laptop from Macbook-Pro/Thinkpad T or X series/Elitebook will cost a lot more than a budget one, even by the same manufacturer (Lenovo Thinkpad T vs Ideapad).
In practical terms, if the intended use is only occasional, the cheaper variant might suffice. If however, one wants the item to perform equally reliably when it is a few years old, the more expensive is a better variant. For instance, something made for long-term regular military use at high altitude will necessarily be of significantly higher quality (and thus, more expensive) than something to be used by a hobbyist using the gear for a week every year.
All that being said, without a personal inspection of the goods, it is still possible you're being ripped off. Or there's a discount or clearance sale.
As a counter example, look up Siachen sleeping bags (-40 celsius) by Gipfel, an Indian manufacturer, costing over EUR 350. Being an Indian manufacturer (with a lower cost base), one would expect it to be a lot cheaper than the EU based ones. But this is still more than the MARMOT.