if you were _already_ complying before GDPR existed (because your business model isn't scummy), then GDPR compliance _should_ cost very little, if at all.
If you weren't complying at all, then adding compliance is very costly after the fact. If you cannot make your business work without complying, then the business must die, as there's no natural right for a business to exist.
if you were _already_ complying before GDPR existed (because your business model isn't scummy), then GDPR compliance _should_ cost very little, if at all.
But unfortunately, that isn't really how it works. Under GDPR you could still find your privacy policy now isn't written in the correct terms, or your previous consents or notices weren't worded properly and might not stand up any more, or your methods of storing data don't make per-person permanent deletion straightforward. And all of this remains true even if you were compliant with all previous data protection legislation (at least here in the UK) and even if you weren't doing anything sketchy with the data and have no plans to do so in future either.
If nothing else, you probably need non-trivial amounts of management time to understand the new rules, some extra legal advice that you're going to have to pay for, and an update of your key documents to make sure everything uses appropriate structures and wording to comply. That alone could already be a significant cost for a small, bootstrapped business, and that's without changing anything about the actual data you're collecting or how you use it.
In reality, all regulations have costs for compliance and those costs typically apply to some extent even if you weren’t doing anything shady at all.