I am trying to find the money value of frequent flier miles and I know
companies like hotels and car rental companies buy miles from the
airlines.

Can you tell me what these type of companies pay for each mile they
buy from the airlines?

Hi r2--I was glad to get to answer this question for you, because I've
wondered about this myself....

I'd previously noticed from their web site that Northwest Airlines
sells miles in two ways, one oriented to businesses, and one to
individuals:

For individuals, at https://nwa.mpmvp.com/buy_miles.asp, the price
appears to be just under 3 cents/mile, plus a $25 processing fee.  You
can only buy in increments of 2,500 miles, and you're limited to 7,500
miles per year.

There's also a business-oriented plan at
https://nwa.mpmvp.com/milesabove.asp, where the price is 2.5
cents/mile, plus a 7.5% excise tax and a processing fee of 0.1
cent/mile.  This plan has a minimum of 200,000 miles, or about $5500.

American airlines has similar programs, but slightly cheaper: 2.5
cents/mile plus $25 for individuals
(https://buyaamiles.points.com/home.jsp) with a maximum of 15,000
miles/year and 2.2 cents/mile plus fees/taxes
(https://www.aadvantage.com/aao/index.jsp?Page_From=OrderMiles)

As I look further, I see that United airlines charges organizations
only 2 cents/mile...  they also have a special "partnership" program
for organizations that want more than 1.5 million miles/year
(http://www.ualmiles.com/RM_Partnership.jsp) but it still appears to
cost 2 cents/mile.

Obviously, everything in life is negotiable, so it wouldn't surprise
me at all if Hertz can get a better deal than this, but it's unlikely
to be documented on the web.

I hope this is enough information for your purposes, let me know if
not!

Thanks for asking,
David