Where have you ever seen a 50% discount for an industrial commodity?
This isn't unusual in enterprise software sales, but it does seem odd for industrial commodities. What I'm asking is why, if supply is so tight, the favoured customers get favourable prices rather than all prices creeping up.
If a customer commits to buying enough over that you expect to break even over the next N years after paying for equipment, labor and other expenses I'll give them that price because I know for sure that I have a factor for N years. I can make a lot of money now selling any extra batteries I make at market price. Even if I can't sell in any more for a profit next year, I keep my employees paid for all of N years (giving me opportunities to find new markets) which is worth a lot in itself.
If I know a customer is well known I might give them a discount just to advertise to others they are my customer.
If a customer is large enough that them leaving would affect my bottom line they get a discount to ensure they stay with me.
If they provide me something other than money in return they get a discount. Auto makers sometimes extend employee discounts to their suppliers employees. Auto makers often do supply management tasks many levels down (my materials are certified not coming from slave labor, and GM did the research to prove it, GM will do it anyway so it isn't a big deal to let me know).
If I expect someone to be a bigger customer I will give them a discount now to ensure they can develop there. If batteries never come down in price from 20 years ago electric cars are non viable so I'll give a discount now because the volume cars represent on a small profit is worth more than all profit at volumes of 20 years ago.
That is just a few honest reasons I can think of now. There are also dishonest reasons that I'll ignore, but sometimes they are real.
Or do you end up in the situation where ordering 3000 costs less than ordering 2500?
It seems to me like it kind of promotes waste since one ends up ordering components that they may have no use for, but maybe it is not that big of a deal since it is common to want to have some amount of spare components when doing a production run. Personally, even if I only need a single unit of some little surface mount resistor or ceramic capacitor I usually buy 100 since the price tends to be like $0.10 each for <10 versus $0.50 for 100, and I can just add the excess to my spare parts collection.