A field to record estimated time (Duration).
A Field to record estimate expenditure/cost (To make this simple just have a decimal number...it may be hard to select currency??)
"My Project Task A"
Start Date = today
End Date = end of the month
Effort = 4 hours (New Field)
Cost = $200 (New Field)
I know this further pushes ToDo further toward Project Management but Effort and Cost could assist in priority setting and are factors in how we decide what to do next.
PS - Thanks for providing a transparent method to put forward product enhancement requests.