A question asked far too often having not budgeted for it properly to begin with.
One difference between a finished visual master piece with a pro voice and a cheap one, from someone with a laptop and mic and charging you a fiver, is the credibility that goes with it. No one is saying ALL cheaper voice options are bad, however, pay for an experienced professional and you are guaranteed audio that sounds high quality and more likely, a voice thats already familiar with big name brands, which brings that credibility to your product or brand too.
It's all relevant. You are paying for years of experience. You are paying for the voice to understand what you are trying to sell or promote, and read it the way you want to tell your story.
Your basic studio fee includes the use of their professional equipment. Then you will pay for usage on top. Be honest with how and where your product is to be used. Unless you agreed a buy out, you don't want an invoice further down the line for usage now you've broadcast it or added it to all your social media channels.
As most professional voiceovers have their own studio at home, it's not uncommon for you to have same day delivery of your audio. If you specify, you can have it edited or de breathed so all you have to do, is throw it on your video timeline, maybe add some processing, adjust the levels with your music track and away you go. A professional voice has seen your script hundreds of times and you can expect the whole process to be quick and easy.
Don't risk damaging your reputation. let the voice be as strong and powerful as your brand.