" knowledge of current Inspection rates on average." 

No such thing.  Geographical location, type of work, length of job, and many other factors come into play.  You will have to figure that out for your expenses and perceived wages and profits. 

E&O insurance, office overhead (phones, faxes, computers, library, desk, electricity, rent-even for an office in your house, etc), bidding time, website, business cards, cell phone, tools, transportation, certification renewals, further education, and much more.  Don't forget any of it.  You will go broke before you start. 

In my area I see everything from $40 to $70 per hour.  Cheapskates trying to horn into something they really don't understand or just trying to steal the work and put everyone else under, up to engineers who figure they are worth more even though they aren't CWI's and really don't understand anymore than the other guys do.  The rest of us are in the middle. 

Then you have to figure out how you will do mileage and travel time and room and board for jobs away from home.

Have a Great Day,  Brent

If you are paying your inspectors, say for chits and giggles 60 per, figure 40% overhead=$84 and then say oh 15% profit=84/.85=$98.82 per hour
You have to do your own intelligence on what the rate is where you live. In some places a CWI can only get $25 or so with fair benefits. In other places you will get laughed at if you offer less than $50 per. And it depends on the industry. The awl biddnez can pay high rates and the inspectors can demand 65 to 90 plus sub. That would be with a API cert or two with a CWI. Pipeline CWI inspectors are getting $4-600 on average per day maybe plus maybe not with additional sub. Depending on where you put the inspector, a $150 day sub rate will not get you a mid priced room. You send the poor guy out and he is paying to have a job, they will be on the phone and next thing you know they are having problems at home they need to go take care of.
If you are working local and not putting out road workers you will need to know the local rates.
Pick up the phone and call your competitors and ask what they are charging for a project. If you do not know how to accomplish that, well you are on your own. Then do the profit/overhead thing in reverse.