It's not expensive if you're okay with cutting corners. Or ignoring users with disabilities. Or shipping a product that's broken. Or dealing with customer support tickets. Or bad press.
Wait, all that still costs you something.
Okay, then accessibility costs something. It's not cheap. It's definitely more expensive than if you didn't do it.
You will definitely pay for accessibility. The only question is how much and when.
So let's break it down.
If you did it from the start
During the project planning phase, talk about it. Where could users with disabilities have issues? How can you solve those? Make accessibility part of the definition of done.
When you're designing, take care to have proper colour contrast, visible focus indicators, a consistent layout, avoid flashing content and design the content to be readable. Having some annotations ready for the tabbing order or decorative images won't hurt.
Then it's time to hand it to development. Semantic HTML and ARIA labels take minimal extra time if you know about it. If you don't, it's maybe 5-10% more effort upfront to get up to speed.
Don't ignore testing. Run those automated tests, but don't ignore manual testing either.
Don't have time? I put together free accessibility checklists for you to quickly check your work for major accessibility issues without feeling intimidated by confusing terms.
Total upfront cost: Negligible to moderate.
If you rework later
You're going to need to do some audit to figure out what you need to fix. Then you need to fix the issues. Then re-audit to make sure they're fixed.
And there's no guarantee they stay fixed because your team doesn't (yet) have accessibility integrated into their processes.
Total retrofitting cost: Moderate to expensive.
If you do it when you're forced
No PR is bad PR, right?! Wrong. You don't want to be remembered as the company that's excluding users who are blind. The internet doesn't forget.
Plus you're likely losing revenue? How much? You'll never know.
But you do know how much you'll be paying in fines and lawsuits. Target paid $6 million in a class action.
And you'll still have to fix your accessibility issues.
Total cost of ignoring it: Priceless (and not in a good way).
Is it expensive? Can we afford to do it?
Can you afford not to?!