The gargoyle pass south of compassion in ilshenar is good, as are the black solens outside Wind.
So are the Earth eles in shame, and the cavern beyond the ratman ruins at Sacrifice.
Levels 1-3 of T-maps have 3 x their map level in gems, IIRC. If you're gonna be needing residue for Imbuing training, go with the maps, to get the items to unravel (or maybe even imbue - my best jewelry, even before imbuing, came from chests).
Map Level / Gems / Items / reg piles / scrolls / gold / time to finish (with a rune library and maps sorted for location)
Level 1 / 3 / 6 / 3 / 4 / 1000 / 1-2 minutes
Level 2 / 6 / 12 / 6 / 8 / 2000 / 2-5 minutes
Level 3 / 9 / 18 / 9 / 12 / 3000 / 4-10 minutes (depending on the number of Ogre Lords that spawn). A quarter of this time will be killing the initial 4 spawn.
You can do 8-15 level 1s before having to put stuff into a beetle or send gold with a Bag of Sending (depending on the amount of ringmail & plate in the chests).
Level 2s, typically only 5 or 6.
Level 3s, you have to unload something every 2-3 maps.
Levels 4-6 continue this pattern for everything but the count of items in the chest (bonus magic items were added, about 50% more than the 6/level pattern indicates).
I personally prefer finding a Gypsy Vagabond at a random spawn in Ilshenar for buying them, as do others in this thread.