Stick it on the broker for 50 gold for a quick sale, or you can leave it sit for awhile for about 1 plat or so. Someone new to the game won't have the funds to purchase that spell until they hit level 20 or so and then its won't be worth going back and purchasing the spell.
It's a level one spell. Conjuror's get another pet at level 12 and since you can get to that level in just a few hours of gameplay, it doesn't make a whole lot of sense to price gouge the general public.
However, someone will get the urge to twink a new conjuror. It will probably sell really quick at 50 gold.