Custom software is expensive to build and usually delivered late and overbudget. Custom software, like a garden, needs to maintained and frequently updated. Especially for security updates. Everyone, well almost everyone, forgets to budget time and money for maintenance.
Before getting custom software built you should check for an existing solution. I’m willing to bet something does exist. Don’t get hung up on the 10% the custom software can’t do. Look at the 90% of the problem it does solve.
Get custom software built when it will save you more time and/or money then existing solution. When your business has outgrown the existing solutions. When it makes sense.