General QA: Pros and Cons (develop vs purchase)

[John Doe]

I have been given the task of figuring out if it would be better to purchase
or develop a new system to replace the existing legacy unix system that is
current in place. I am trying to do this as openly and honestly as possible
due to it will also be my responsibility to help install and maintain this
system for the long haul. It would be nice if anyone could reply with their
pros or cons for such.

The system will be a retail system which would have a full general ledger.
Currently we use a custom built unix/filepro system that has ran since mid
80's but only a single programmer knows the code/backend programming which
leaves us up against a wall should the existing programmer croak. We
currently have the full source for both the existing system (pre
basic/filepro language) and a fully functional but built in m$ access
accounting program. The owner/pres is a customizing freak. For instance
you will have 10 reports that say the same thing but shows it a little
different or you will be required to add/remove this from menus and display
them how he wants. Other more complex examples would be that a sales person
that sales a wigit at this location on that day would get a different
commission rate than if the item was sold at X location on Y day. According
to him these are requirements of a system.