Hi, I have two points:
People should be unable to upvote a deal if the are in the referral system - People are upvoting deals or posting deals based on generous referrals. This is an abuse of this site and promotes average deals with referrrals.
Combination posts - eg. posting a phone and a USB cable. People upvote deal because the USB cable is cheap, but inadvertantly promote the phone. Solution: Each item in combination posts should be upvoteable.
Interesting points and they should be considered
No sure how much an issue the first point is. Another solution or alternatively an additional limit, is that the only referral is that which is randomly generated rather than the current poster and random referral links being shown.
as for point 2, the way you put it, that is definitely gaming the system