For reference, these are the substantial sources of dragonite that I know about:
12 dragonite per day from dungeon battles (120 dragonite per perfect run at depth 20; chance of a perfect run is 10%)
60 dragonite per day from dungeon purchase (300 gems)
~4 dragonite per day from merchant offers during delves (30 dragonite for 150 gems) (3 delves * 8 nonboss battles * 15% encounter chance * 40% of encounters are merchants * 10% as a guess of chance that dragonite is offered based on the number of distinct merchant offers)
50 or 100 dragonite per week from underspire (requires substantial gem investment, perhaps about 1000 gems, decreasing slightly as we better understand underspire generation and strategies)
?? dragonite per hour of grinding E1/paloozas during vault weekend (merchants, gnomes, keys)