There have been problems with both carburetors and fuel pumps.
The two biggest problems I have come across have been:
The seat that is in the carburetor has 1. NOT been pressed completely into the body of the carburetor. OR 2. HAS been pressed completely pressed into the body of the carburetor, but leaking fuel past the sides of the seat(between the seat and the body).
Also the fuel pumps that have an aluminum housing, have been leaking, and some worse than others. If you install a fuel pump repair kit, most of the time it will NOT correct the problem for very long.
The diaphragm in the fuel pumps have been leaking fuel past the diaphragm, and back into the engine through the impulse line.
In both situations if you check your oil and it seems VERY thin, or smells like gas is in the oil, it will be one or both of the above.
Also if when you try to start the machine, and smell strong gas fumes, remove the air filter and see if there is fuel standing in the intake pipe. If so refer to above.
As far as replacing it yourself, it is an easy job to do, and if you decide to take it in to the shop for repair, it should NOT take anymore than about 30 minutes.
The price of a replacment carburetor sounds about right.
Hope this helps some.
Jeff in AL