control...
I had to think on this for a while. Control over something you already sold covers a lot of ground. I think the only time a maker really has any control over a product which has already been sold, is when the buyer signs a contract which covers the use, resale, disposal, etc., of the product, or when someone callously handles a product in a manner which could or does cause monetary or reputation damage to the maker's business.
Resale issues are many... There are price, condition, endurance and probably other issues which could be considered.
How much an item resells for has been an issue with many folks. I think any item is worth what one person will accept in return for it to leave their ownership and what another person is willing to pay for it. If a guy wants to resell a $20 cue that is the last one in existence and another person wants it so bad he's willing to pay $500 for it, then it's worth $500 at that time and the maker has nothing to do with the price, unless he has some kind of contract that covers it.
I think that someone who makes a product has to take all this into consideration when he sets his price. If someone re-sells your stuff at a higher or lower price, are you going to lose any sleep over it? A maker has to set a price that he can be comfortable with, regardless of the future of that item.
What if I bought fishing lures direct from the maker in bulk amounts, then I sold them for less than the guy at the discount store could sell them? I think that unless the maker has a contract that he requires you to sign at the sale, once you pay for the items, you own them and all the rights/responsibilities that go with them, so there is nothing the maker or the retail guy can say about what you decide to do with them (unless you are purposely doing something to damage their business or reputation). I mean, who's to say the wife didn't tell you to sell all 5000 of them at half price to get them out of her house???
How many times an item could be sold before it damages a maker's business and reputation... I think that might depend partly on the honesty of the reseller and the condition of the item being sold... whether it has been kept in A-1 condition, or it is obvious that the item was originally bad, or was abused by someone. A certain amount of wear and tear is expected on most resells, if the item was used much.
I think there's a lot of good and bad that goes into reselling anything. I think there's a time where it could become a legal issue, if it seriously damages a company's business, but for the most part, when it's paid for and it's delivered, you no longer have any control of what's to be done with it. If a maker is feeling like he is being done wrong, I think he should mention it and hope the guy or gal doing the damage has the decency to make a change that fixes the problem. But, if the problem gets fixed, that isn't really control. That's just being lucky you're dealing with good people.

(or you got a really good attorney!)