I would say that Kentmere VC Select and Ilford MGIV RC are about the same weight. Kentmere emulsion is about 2/3 to 1 stop faster than standard Ilford; print quality, and tonality is very close, but I find that Kentmere does tone a lot better. Ilford MCIV RC paper in the 10x8 size is heavily discounted, but their other sizes and types are dearer.
I imagine graded papers are dearer because of their lower sales in comparison to MG papers, I cannot see that their actual production cost is much different to MG paper, but the production/sales volume would be a lot less.
The only certain way is to try these papers for yourself, most are available in small packs. Kentmere, and I imagine Ilford will send you a sample pack if you ask nicely.