Vendors won’t be buying from RISC-V, they’ll be buying from someone else who’ll use that open source design.
By not paying for R&D and enhancements, that OEMs will be able to offer lower prices.
You might be replying to the wrong comment by mistake as I listed a number of reasons people might like an open ISA and reference implementation. That OEM's will repackage it for those purposes doesn't contradict what I said.
Have customizable cores to add HW accelerators to like Cavium's Octeon III's do.
Things might get cheaper over time as big vendors buy in volume and that money goes back into enhancements.