Hi Anlor,
I am happy you did not take what I said personally, as obviously I do not know your nor I have idea what book is about. I think it is typical for Aspies to make speeches rather than talk to people, and this is exactly what I did when I replied to your thread - but I did not speak about particulars like you or your book.
I am where you are now - I am almost finished writing my non-sci book and I was reading on publishing, self publishing etc over the last 6 years. So I do not have actual experience, but some second-hand knowledge. When it comes to marketing your book on your own, it will make sense only if 1. you have money for it and 2. your aim is to self publish. Alternatively, you can publish without much spent on marketing in kindle version - Amazon makes it very easy for first time authors these days. But, unfortunately unless your book is bestseller, you cannot expect sales this high from self publishing, despite the fact you get to keep the lion's share for each sale.
In every other case, you will need to get a catalogue of literary agents in your area and contact them, preferably starting with the ones who are dealing with your kind of writing/subject/audience. Once you will find an agent who is interested, I believe the next step is to sign a solicitors agreement and let them read your manuscript. The role of a literary agent is to assess the content, solicit your manuscript for sending out to publishers, and finding a publisher on your behalf who will print, market and publish your book. Agents do charge a lot on your book sales, however when you think about publishing for the first time you may think of it as an investment: literary agents know people and have connections, and they are capable of finding a good publisher and negotiating a good deal for you. So the money you pay them, in my view is sort of investment. The first time you publish you trade your profit for name recognition and prestige, which should make it easier to make money out of your second publication.