2k+ it should sell.
3k - 4k has potential with all unlocks open.
I sell level 1 caly mythicals for around 1.5k, for fast sales. Mainly because its very hard to find buyers for trained pets at higher prices (despite the effort and time).
There will always be a buyer though for a Lava or Royal, still quite sought after. I've never failed to sell a Lava or Royal. Depends what you're prepared to let it go fir I guess.
Rick