Actually, you're right - it is easy-peasy and you definitely don't need to go to the expense of a shop rebuilt. I agree with Mark that having two pumps works great - you can rebuild one at your leisure after popping the new one on. I do this with both my genset and my main engine water pumps - have rebuilt them both many times over the years.
In lieu of a press you can just carefully tap out the shaft using a socket from your socket wrench set as a "pusher". On reassembly you may want to put parts in the freezer and/or hot water to make them go together more easily. Sourcing parts is easy.
Have fun with it!