Good suggestions Stepdad though there could be problems with reviewing for quality as that requires a person's opinion. How will a 'quality' product be defined? The criteria would need to be set out very clearly. Also it can be difficult to predict what the punters want - I have been quite surprised at times by the popularity of certain items.
Also, by nominating 'vendors' as volunteers in the process of approval, you could also be creating problems. How do you prevent prejudice? If a person accidentally offends one of these vendors couldn't that lead to submissions being rejected or judged too harshly? Also, if you submit an item that directly 'competes' with the vendors own work, couldn't that also cause problems?
I say this, not because I think your ideas aren't valid, it's just that I can see the potential for other problems to arise. Will it become a case of who you know rather than what you create? [Point in case, I have noticed that some of my products which are of a particular type always attract a one star rating - interestingly it is the items I've created which are similar - but not identical - to another contributer's works. These items are unusual which is why I provide them. So what would happen if the ratings were done by the 'competing' vendor and that person happened to be chosen as a quality reviewer?
Just my two cents worth.