I would also add that you should NOT put it off. That’s an 11 year old belt and it won’t give you a hint of warning. One moment your engine will run. The next it will be dead as a doornail and you will be stranded where ever that happens. Hopefully you won’t be stranded and at the center of a an accident that you just caused by having your car suddenly die in the middle of traffic.
While mcp is probably right about the quote, you cannot use internet parts prices to even begin to guess about actual repair costs. The front of your motor is crammed up against the passenger side frame/fender. Yet the front of the motor basically has to be torn down to change the belt & pump. That’s the reason the pump gets changed. The devil is in the labor, not in the parts.
However, I will note that you are giving $500 as a wholesale parts cost for this “kit” so there may be more involved than meets the eye. The typical parts are the belt, a new tensioner, and the new pump. There is no way that this runs $500 at an internet “wholesale” price. So perhaps you could itemize everything that is involved and then maybe $1300 might not look so bad.