I see. Thats quite intriguing. Never though about tyring to farm the low level quests to get the first Garden. Is the first Garden worth the effort ? (cant really recall it as it has been a long time since I visited that one).
As far as I can tell in 12-4 the ampys keep dropping relatively at good rate (not the best but you know). However seeing your comments I think I will try to run the -3 map a few times for comparison.