My 7.5' frame-mount hoe cost about $6K USD when purchased with the tractor. I would say to date (~150 hours of hoeing) it's probably paid for half of its cost. I've installed septic lines, buried a 500 gallon propane tank and trenched for the lines to house, buried gutter drain tile, dug footers for a retaining wall, installed 40' of 2' diameter culvert pipe, dug a garden pond, removed several large stumps, placed a heavy concrete fountain in the garden pond, removed all the old shrubs from in front of the house, buried the neighbors dog, buried a dead deere. Have other projects planned for it this spring too. Need I say more?
Will it ever fully pay for itself? Maybe, maybe not. But I chose to buy one because it's convenient and fun to do yourself without rental and transport hassles, and it really saves your own body too.
I have not been paid to do anything with it, and don't plan to ever try. I will ocassionally help out a neighbor or friend, but that's it. Didn't buy it to make money.