Hey Francois,
The industry tends to charge more for floating licenses (a.k.a. "site licenses", a.k.a. "volume licenses") than they do for per-machine or "single" licenses.
A few examples come to mind (I'll limit myself to talking about companies that aren't yet LimeLM customers): PTC Pro/Engineer, Matlab, and Microsoft Volume Licensing.
In each of these cases "single computer" licenses can be bought easily from their stores or from their resellers. Also, in each of these cases the "volume / floating" license end-costs are a good deal more than single license costs. Unfortunately there's not a whole lost of open data on any of these companies pricing models.
- Price should be set a bit higher for FL (20%?)
About a decade ago I discussed the costs of Pro/Engineer & Matlab with someone who did the purchasing for the local University's Mathematics & Engineering departments. He was in charge of buying licenses to cover nearly a thousand computers throughout a few buildings. And of course, like any University, there wasn't a ready stream of money to just go buy a thousand individual licenses and install a copy on each computer. So he opted for the middle ground of buying around 100 "seats" of licenses (or 100 "slots" in our TurboFloat parlance).
Each of these "seats" cost -- if memory serves -- around 2x the cost of what it would've cost him to buy "individual" licenses for 100 separate computers. And of course that was the lower "education institution" price. The corporate price for floating licenses was more -- unfortunately I don't know how much more because the prices weren't and aren't readily available.
Microsoft tends to go in a different direction. They offer "volume licenses" cheaper than the individual licenses, but they require you buy a minimum of 5 licenses to qualify. Also, complicating things a bit, Microsoft offers volume licensing that can be installer per-machine or using floating licensing. Here's what little public information I could dig out about their program:
Is there a mininum number of licenses that must be purchased under a Volume License Agreement?
Yes. The minimum number of licenses required for a Volume License Agreement is five (5). However, the five licenses can be made up of any combination of products. Quantities of less than five can also be purchased economically by making up the additional license using an inexpensive "make up" product SKU.
Once the initial Volume License Agreement is in place, additional licenses can be added to the Agreement in quantities of less than five. For example, if a company purchases five Office 2010 Professional Plus licenses under a new agreement, three months later the same company can purchase one additional Office 2010 Professional Plus license under the same agreement. The minimum license number therefore only applies to the initial Volume License agreement.
So, different companies have different methods of pricing, but all tend to agree that a higher price is in order (either through higher pricing or through a greater "minimum" order).
I hope that's of some use to you.