Fees vary widely. Sorry for the vague answer, but that's the reality. Don't go on just hourly rates. Higher rates often (but not always) reflect greater efficencies. For example, I spent two weeks or more working on my first Office Action (response to a rejection by the Patent Office) back in 1991. I now do them in a day or less. My patent applications are less expensive than they used to be despite increases in my rates over the years because they take less time than they used to.
Some charge for initial consultation. Others don't. Some take work on contingency (no money up front but a share of the profits). Others don't.
Personally, I think investing ought to be left to professional investors, but I do recognize the "Catch-22": most investors won't sign an NDA, so you should have your patent application filed before talking with investors; but patent practitioners are recommended to get the patent application on file, so you should have some investment money to pay the patent practitioner. It's really hard, and I'm sorry it's that way.
I suppose it's no surprise that invention submission companies are popping up all over the place, claiming to combine seed financing with IP services. However, most of those are scams and, if there are legitimate ones, they're like most other hybrids -- instead of being good at two things, they're good at neither. Think of combo road/dirt bikes -- not particularly good at either. SUVs -- not great offroad and horribly bad on-road. Amphibious aircraft -- not as good (fast/efficient) as either dedicated seaplanes or dedicated land-based planes.
I wish I had an answer for you. I don't. Launching a business around a new idea is hard. For what it's worth, some people have had good luck approaching manufacturers with no more than a prototype and an NDA. Those success stories are few and far between, but they exist. And, not all investors refuse to sign NDAs.
I hope that helps.