There are many types of website reviews and audits that test and review the user experience, user interface, usability, accessibility, information architecture, conversions, etc.
They all vary in scope and methodology....
I'll be honest and say that I don't know what some of this stuff is. So, I would be hard to sell and would need education first. I think that a lot of people are not looking for these services because they don't know what they would be buying.
And, this is probably a really hard time to sell these services because a lot of people are really busy and broke and shot mentally because their income is down and they are spending a big pile of money, trying to chase penguins or pandas or pigeons away - and they don't know if their efforts there are going to work well enough that they will have a site this time next year.
Another problem is that I would be worried that the news I will get back from any audit will be to do lot of work that is beyond my budget and abilities.
How much would you be willing to pay?
That's a really hard question because I don't have a frame of reference. I paid SiteTuners a few thousand a couple years ago to improve some sales pages and thought that I got good money's worth. Based upon that, I don't think that the cost of the analysis scares me half as much as the cost of implementing the recommendations. And, I might need technical help getting that work done.
So, because this is untested ground for me, I wonder if I could get a "low hanging fruit" analysis from someone who knows a bit about my site, my employees and the nature of my business.... because any recommendation that I get might not fly on one of those fronts.
The reason I say... "low hanging fruit" is that I think that a person who knows about about these types of assessments would take one look at my site and scream OMG!! and have a big list of stuff that needs fixed right away.