How Much To Spend On Accounting Support?

I had a meeting last week with an accounting firm because I’d like to outsource my bookkeeping and get help with my financial planning. They came back with three options, the cheapest of which was still more than I expected. It would end up being about 8% of my gross income to hire them to do my bookkeeping, my taxes, and to give periodic financial guidance (annual meeting). Is there a rough guideline, say in percentage of business income, to help decide what makes sense to spend? i.e., is 8% normal? High? Low? Thanks!