re: "I haven't the foggiest clue how to price my project. I know what I want done — edit an audio and add graphics to create a video — but I'd love advice on how to research what a reasonable price would be for the work I want done. It's not in my expertise. Thank you."
This is exactly what you need to write in a job posting, to hire some freelancers to consult with you using hourly contracts.
Copy this text and add:
"This job posting is to hire you just to talk with me over the phone or Skype so I can ask questions and get feedback about how much my project will cost. I expect this will take between about 10 and 30 minutes."
Hire 5 different freelancers, representing different skill/experience levels and different hourly rates.
You will obtain the insights you need, and you may also end up meeting people you would actually like to work with.
Just make sure that when you talk to these people, they log time so that everything you discuss will belong to you, and so that you do not violate any Upwork ToS.
You do not need to hire 5 freelancers. When you post your job, give as many details as you can concerning what you require and put $5.00 as a placeholder and say why you have done this and indicate whether you want entry level, intermediate or expert.
You will get a lot of replies, so you will have to do a lot of sifting. My advice is to check each profile whatever the level. You might find an entry level who exactly fits the job and the budget you may have in mind .
But you do need to know how much you can afford. So I think you should do a little online research so that you know more or less what you might be letting yourself in for budget-wise.
A placeholder budget, as Nichola suggested, is fine, but I wouldn't recommend $5. As a freelancer I filter out jobs with budgets under $100, and I doubt I'm alone. Also, some clients who say $5 really mean $5, and you don't want to be mistaken for one of those. I suggest giving a budget figure that's plausible.
Another thing I've known clients to do when they don't want to state a budget is post the job as hourly (paid by the hour). You can change it to fixed price later, when you make a job offer.
Also bear in mind that freelancers may not be able to quote a fixed price immediately. They may have to ask you for more information first.
Can I explain "everything you discuss will belong to you"?
When you HIRE freelancers using an hourly contract, then EVERYTHING that they create while logging time on your contract belongs to YOU.
If you HIRE freelances to consult with you, and then you have discussions with them about your projects, then the discussions you have with them belong completely to you. You own the intellectual property rights to these discussions. Completely.
It means you are allowed to use all of the information and ideas gleaned from these conversations.
You don't need to hire 5 people. If I were you, I'd post an hourly project. Collect bids, and then ask the people you like to give you an estimate on hours. Most professionals can get you a ballpark figure. Then just set those hours on the weekly contract.