Does this constitute harassment?

[MaLTRaiN]

Your mistake. You shouldn't try to sell an item on the chat. The chat isn't for that.
The other player? Two things. One, he was angry for your ad and gave you a lesson. Two, he could be balancing the price because he thinks you're taking advantage from the people.
If you spend only 1k for the item, just move on and keep crafting and selling.
I'm a crafter too, sell for big profits too and undercuts happens all the time.
Sometimes you win, sometimes you lose... you don't cry over business.