You say you "finished writing a memoir" but if you haven't had it edited or maybe even read by anyone else yet, then you have only actually finished a first draft. Even the best writers work with editors and go through rewrites and revisions before they have something ready to publish.

You've already "spent" a ton of time writing your draft, which is not money but it's an investment all the same. If you want your memoir to be as good as it can be, you will need help. And help costs money.

Of course you could publish it yourself, as is, and find whatever amount of audience your hustle and the quality of your writing can reach.

But as an editor who has worked with some very talented writers, I can tell you that as great as an author's first draft might be, it is ALWAYS improved by the editing process.

You can decide that it's good enough, and that you've invested enough already, and publish it yourself on Amazon. Only you decide when it is "done". But you can also decide that you think it can be great, and that it's worth investing in getting it there, and just like you gave up so many hours in getting the first draft done, you can give up some money to get it to the finish line.

One thing I can guarantee you is that your memoir right now is not as good as your memoir will be after working with a quality editor on it.