For short range, say 600 yards or less, I might agree with the other member about a red dot scope on a .50.
Now, here comes the reason to buy the best glass you can afford to put on a .50, you are going to shoot it long range at least once in your life. Show up to the range/area where you plan on doing this and have a red dot on it and you'll cry like a little bitch!!! For the rest of the time you own it and don't have a backup scope for long range shooting.
The day you get to shoot your .50 out to 2000 yards +/- a few hundred yards, will be the day you understand "buy once, cry once"! That shit eating grin will have to removed from your face with a jackhammer! Then throw in the fact that with quality glass, you can actually watch the round fly down range to the target. Yes, it's possible to do as myself and others that own .50's routinely call each others shots as that huge ass bullet displaces a lot of air going down range.
Of course the downside is the price of one of these scopes, which start around $2K and only go up. So save your pennies, use a lesser scope on it until you can afford the one you want and then move the old scope to another rifle and put that sweet scope on your. 50.
Don't forget to relax and enjoy shooting your toy.