First of all, bear in mind that Springbank itself is a much sought after dram, and demand often exceeds supply. So in regular Springbank, you already have a very respected & (usually) high-scoring whisky, that can be hard to come by. This is a recipe for higher prices.
So when the distillery then changes its production configuration & malt bill for just one month of the year to produce a different whisky (i.e. Longrow), you can imagine that this is a particularly rare & exclusive dram. Now good quality peated whiskies are in huge demand - there's only so much Laphroaig, Lagavulin, Ardbeg, & Bowmore to go around. So - once again - when a great tasting peaty alternative turns up in small quantity for a short period each year, the bottler can charge a higher price, knowing that the market will bear it.
So - after all that - is it worth it? IMHO: Yes!
If Longrow tasted unpleasant, or bland, or just plain ordinary, then it wouldn't hold any appeal in the market place, and people certainly wouldn't pay the higher price for it.