>> I may have to raise the price for my application to cover for the added cost which will make me less competitive.

The insurance requirement is an indication that you may have a bad client.

A client who does not want to take responsibility for final system testing.
A client who does not have the patience to explain IN DETAIL exact system requirements.
A client who does not understand just how intricate the logic can get, and that they will have to make clarifications to requirements later - business issues that neither they nor you can possibly foresee.
A client who wants magically perfect results.

In short, the real cost is not the insurance, although that is expensive.

The real cost is this - you will make it easier to sue you than to do the hard client-side work of making a functioning program.
(And most people can be counted on to do the easiest thing)

Think of how much time you will lose when he sues you.

Just the time and business interruption would be catastrophic - and that part is NOT covered by insurance.

If you can explain these facts to him and he settles for just general liability insurance, he may be a good client.

If he still insists on professional liability insurance, he is not a good client, run away and don't look back.

Best,
Michael