I decided to do a 50 quest profit challenge to see what quests are most profitable and available for any user to complete fairly easily. Please note that results will vary. Prize wins or value of the prizes are not guaranteed.

Rules I followed for this challenge

-Complete all quests, unless total cost of all items asked for costs more than 50k.
-Purchase all items requested from either user or Marapet shops using MP only.
-If the item sells in a BP/RP shop, purchase the item from a user shop for MP.

With these rules, the profit calculations will be based off of if you had to purchase all of the items in order to complete the quest. For all of these quests, if you already have a stockpile of items in your attic for questing purposes, the profits will be even higher.

Borak
MP balance: -119997
RP earned from restocks: 654
Prizes won: 11
Approximate profit if sold prizes at current prices and RP at 1:17 ratio: 285068 or 2.375x what was spent. Notes: I averaged a prize approximately one every five quests.

Candy Tree
MP balance: -268511
RP earned from restocks: 60
Prizes won: 5
Approximate profit if sold prizes at current prices and RP at 1:17 ratio: 2528991 or 9.419x what was spent.
Notes: I averaged a prize approximately one every ten quests. One of the prizes I won was valued around 1.5mil. Without that prize, the profit was still around 1mil after completing 50 quests.

Carpenter
MP balance: -218532
RP earned from restocks: 844
Prizes won: 8 and a toy fix
Approximate profit if sold prizes at current prices and RP at 1:17 ratio: 1621499 or 7.42x what was spent.
Notes: If I kept the toy blocks won from questing, average cost of each block would have come to 27317 each. Obviously if this quest is part of the weekly benefits where double prizes are won, the profit would be even higher and it would be more worthwhile completing these quests.

Cosmonaut
MP balance: -212295
RP earned: 1172
Prizes won: 10
Approximate profit if sold prizes at current prices and RP at 1:17 ratio: 756664 or 3.564x what was spent.
Notes: I had to let one quest time out due to the item not being in a Marapets shop to restock.

Desert Spy
MP balance: -250313
Spy Points Earned: 27879
RP earned: 1282
Approximate profit based on selling Spy po