Okay, I'm not the best at explaining this kind of stuff but you can send someone an item in your inventory (i.e. a fairy mushroom, they're usually preferred for a money exchange) and there's a button that looks like a letter with an arrow underneath. Click that. Once you do a screen will pop up asking for the recipient, where you type the player's username and the CoD fee, were you enter how much you're asking for in return. In this case 4000. If you need more info or I was too confusing please tell me, I'll try to be clearer or help with that.

That was a perfect explanation. Thank you

Lots of Kelpari throughout the hatchery
Lots of reguar ones for under 2k!
All regular ones are under 4k
Two different types of themed Kelpari (prices vary)

Lots of Kelpari sales in the stable as well

Tons of other pets throughout the hatchery and stables

PM for price negotiation or if you see a pet you want that's not marked for sale :)