i have a set of the above wheels, only a couple of years old. the rear rim got buckled and is not fixable. can the rim be replaced on these and is it economically feasible to do so ?

Yes, no.

Speak to a mavic dealer or direct with mavic uk, but as njee20 says, it will be expensive, probably more than the £180 I was told by Mavic service centre for rebuilding an ST rear wheel with new rim and spokes. IIRC it was roughly £80 for the rim, £60 for the spokes, the rest labour.
Edit:
A new wheel is £400 +

I’ve replaced the rims on my set of v-brake mavic slr’s myself, i reused the spokes as there wasn’t anything wrong with them and from memory the rim cost £55 or thereabouts.

thanks very much guys, i’ll give them a ring

I replaced an slr rim about 2 years ago. The rim was £120!

I swapped a rim on a rear SLR, it’s a really easy job as the hubs direct the spoke to he appropriate rim hole.
I used the original spokes ans all is well.