creating “random” stats on the item (like diablo) is fairly easy to add. It would also be fairly easy to do with just a little research.
The basics would be that when the item is “spawned” (or identified) it does a random roll using a random int in range options for the different stats.
so you could have it roll a determining stat roll between 1-100 on int, vit, AS, Crit etc and then the 3 stats with the highest rolls are the ones that are added to the item, then they each do there own stat rolls between an INT in Range of lets say 5-10 and then multiplied by a “item level” multiplier. So if a level 20 item rolled a 8, it would then be multiplied by the 20 = 160 int (min roll of 100 int and max roll of 200 int). this is very basic way you could do a system like this.
I fear that some people are under the impression that marketplace items are going to be tailored to their own game, this is an amazing inventory system but that’s what it is, a inventory system. You still need to build on to it with all the other systems you want for your game.