As long as you loot the maps yourself, they are extremely profitable. I never buy maps because it takes a lot of the profit away. I get most of my maps from Maisma so it is 0 cost. The ones from the chest are level 6 and you can level 5 on the body. 5k per level so 25k to 30k right off the bat. Most of the arties are easy to find cheap so I usually unravel them but you can put them up for like 10k and they usually sell ok. If you have an inbuer, you can unravel everything or just the stuff that unravels into essences which is what I do. The sot's can be sold for a decent amount along with the essences that come in the chest. There is one per level and can usually be sold in stacks of 10 for anywhere from 100k-500k depending on server. You also get the gold and loot from the guardians. That usually adds up to 10-20k for 5th and 6th level. On the level 6 chests, there is also a chance for a level 7 map. I also manipulate the chest (that sounds bad doesn't it? lol) when I am done pulling what I want. I can usually get an extra 10-15 mobs to spawn but pulling something up and letting it fall back in. People also like the skeleton keys and pet treats. If you look at it as a per chest profit, then it doesn't seem like much but they are quick and easy to do. They add up quickly and are fun to do.
I know this is an older post but decided to answer it just in case someone else was wondering the same thing. Treasure hunting and fishing are my main pleasures in UO.