“It is regarded as najsh when the seller apparently insists on a certain price for a commodity which costs much less than this so that the buyer may take in for the highest price possible (in other words earning an unreasonably high profit).”

What if there are people who are in so much habit of bargaining that the seller is forced to quote a high price for his commodity so that after bargaining he is able to earn a reasonable profit and in case the buyer does not bargain then the seller can just offer a discount in order to avoid profiteering.

Is this permitted?

I might be wrong but I always thought that 2 wrongs do not make a right and I think this does apply here too. The seller is obliged to do what is legally right and the same applies to the buyer and neither of them must turn to haraam ways just because the other is doing it. [1]

Having said that: the seller still has a right to charge whatever he wants provided the product is worth the price.

References:

[1] Sh S Al-Fawzan, A Summary of Islamic Jurisprudence, 1/9