They are more expensive than many bolt guns, true, but certainly not all.
(Actually, the .243 version is mentioned on the linked website - it's just in front of the 7mm-08 item.)
But they work really well IMHO. And as the OP mentioned, semi-auto platforms based on the AR-15 are far more commonly found now - and are written up in hunting magazines. Given that so many guys who cycled through the US military over the past 9 years of conflict now are very familiar with these platforms, I wouldn't be surprised to see them expand into hunting even further, sort of like semi-auto pistols replaced revolvers throughout most of the law enforcement community. We'll see...
I shoot both, and prefer hunting with the R-25 to using my Ruger bolt guns.
Just a personal preference...