XP licensing question

I have a friend who has his own business and uses 8 workstations in his shop, currently he is having some problems with his computers. He has called a professional computer service and they will come in to see if they can fix the problem, if not they would backup the data and install XP on the workstations. They quoted him a price of $50 per workstation.
Here is my question: how can this be done considering the price of a legal version of XP?
I assume they have access to some bulk OEM(?) licensing. ANybody know the specifics about this?

Thanks

Why not ask them the type of licenses they are offering? $50 seems reasonable for an OEM XP upgrade license.

You can definitely buy site licenses, but I have no idea what the contract price is. A lot of times there's separate third parties that handle nothing but the licensing, which this might be the case. This is only for a few workstations but if the same third party also handles a lot of other businesses, especially ones with thousands of employees you can imagine there's probably some heavy discounting going on for volume. Plus it's only licensing, they don't really need to manufacture anything which saves a lot of money, and also the third party often will be obligated to be the first line of support. You can find OEM at some places bulk retail almost that cheap anyway if you really look hard.

Thanks for your responses. I guess to get a good deal you have to buy in bulk.
I was going to do my friend a favour and back up his data and install XP on his computers for him, but he would have to pay a much higher price just for XP even if I did not charge him for the labor. So I guess he will go with the service company.