Yes stay away from UE, carrots are fruits here, snails are fishes, they tell you what kind of electric bulb you can use, all that nonsense in life. But its quite good if you have Monty Python sense of humor.
As to unreal engine, I would say you cannot afford anything else, most game devs cannot. Or you will not get anything better for that price. For starter forget about anything bigger than tiny RPG, shooter or good platformer. Take look at steam greenlight most popular games, you just cannot do better than that until you have some real budget. So your worries about MMO are like me worrying now that i get too much tan in Australia, all while i am in Iceland.
And gross income (in case of UE4) would be higher than buying license (writing engine) only if your game sold few millions copies. If you that lucky to sell your first game in such quantinty, i bet investors would be kissing your *** and begging to have their baby.