Question on purchasing characters

Hey i'm fairly new to Warmane, and i know that it requires being above level 55 to create a death knight. I know it's possible to buy characters, but i was wondering how this would effect the game, and if i would be able to create deathknights on other servers afterwards as well. Also a sub question, i've been looking at the list for possible trade options, and it seems as if theres no possible way to find a character for less than 30 coins. Is this the case or do I need to look harder?

30 coins is the minimum/default price for naked fresh 80, can't be set lower than that

You can create DK only on the realm where you have another character that is at least level 55. But if your account is premium, you should be able to create a DK on any realm without having other characters.

thanks for help guys i appreciate it!