What brand are the cutters? Are the sets, a complete set, by the same manufacturer? What size is the arbor (hole size)? The most important is what DP sizes are available? If you tell us what size you have a chance to purchase, a better recommendation on which ones are "more usable"
I bought a set of 4DP cutters, 1-1/4" arbor hole but they are mixed manufacture (all U.S. made) for $108 shipped, from eBay. Just bought a 16 DP brand new China made with a 7/8th arbor hole $68 delivered. I haven't used the china set yet but I would have preferred something made in Europe or North America with a 1" or 1-1/4" arbor hole.
My VN universal dividing head needs gears for various rate of twists, these appear to be 16DP, so is the worm wheel in my Stihl cultivator. So sometime in the future, I will have a need for the 16DP cutters.
What I'm getting at is that your friend is asking a very fair price, buy what you can afford but know that unless you have a real need the cutters will just sit in your tool box. If you are like me and watching your tooling pennies you need to buy wisely. With that said, complete involute cutter sets don't come onto the market very often. Maybe you should buy all that you can now, instead of kicking yourself a year or two from now.
Mike