I haven't found anything on this site unless I just missed it. If you see it can you post a link? I'm going to try and make some calculated guesses later.
If you have the best you can buy from the Pet Manager there's no need to upgrade (unlike with wolf gear). If you don't have the best... desummon your hatchling (or simply have the weapon/armor in your inventory not the hatchling's), go to the Pet Manager and simply look for the upgrade equipment link. You'll need gemstones for each level upgrade. You can't jump straight to the best. You must upgrade one step up at a a time.
Yeah I have the torturer but I want to upgrade much higher... all the way to the top. If I had the upgrade info I can calculate the cost in gemstones based on current server tax rates. If it costs too much then I'll just go buy the weapon outright and sell my old one. I've done the upgrade for the wolf gear on my old server and the running back and forth was a pain but the tax rate was cheap (2% - Gustin Server, Innadril Castle, RC owned it then) so it was worth the time.
Im going to jump in here as well
i had to follow the upgrade route to get my hatchling gear as well
hint - as far as i can tell for now, there is no additional adena costs in goddard...
so you buy the gemstones in the cheapest town and tele there. its just the gems to upgrade
and top one i think i saved 500k adena.