Ok just a couple of things. The Royal Purple that you get for under $100 is a Group IV oil, so compare that to the Motul 8100 which is also Group IV.
If you want to compare the 300V then you can only compare that to the Royal Purple racing oil which is around the same price as 300V, im pretty sure it is a Group V oil, but not 100% sure on that one, will have to speak to the Royal Purple rep next time i see him.
Problem with Royal Purple is that it started getting a great name for it self when Street Commodores did a test on all the oils in the country and Royal Purple won it be a mile stone, all the other brands including Motul performed horribly. Suddenly they got the attention of all the oil companies and they went "Hang on a sec, wtf is going on here!", so they investigated it and a law suit became of it. The problem was Street Commodores used a machine that didn't simulate engine loads on bearings (i believe it was a gearbox load simulator from memory) and that's why all the oils performed so badly. They published a big apology but not many people saw that one, they just remembered Royal Purple dominating it, hence their great reputation began in Aus
Nice history lesson for ya.
Nothing wrong with Royal Purple, i sell heaps of it and it's a great oil. If i couldn't buy 300V at my work i would go the Royal Purple 10W40 because Motul don't make a 10W40 in a Group IV oil.