Anyone not building a proper rackmount server is unlikely to need more than Unraid Plus. Which is 89 USD without a discount. Said discounts vary but are generally 20-30% or straight up 10 dollars, which gets plus down to 60-70 bucks. Unraid Pro I think is where you start getting into discussions of if this is a good decision, but we are looking at 90-110 for that.

Which is not nothing. But Plus undiscounted is about the price of a 4 TB drive. So if you can't afford a license you can't really afford to run a NAS with any degree of recoverability. At which point you are probably better mounting the drives as individual un-RAID'd drives and spreading files across a file system. Because, at that point, you can't recover from any failures anyway and this at least still guarantees access to your remaining files if one or more drives drop.

And if you are going big enough to need more than 12 drives in a single system (and I say this as someone who currently has 16 in his NAS...): That is when you should not be using unraid. Multiple physical servers set up as a ceph array and dealing with a lot of smaller zfs raids of varying sizes is the way to go but... you are losing a lot of storage to parity for something that likely isn't worth that level of redundancy. But you also start getting into a discussion of "what is my time worth" at that point because... Ceph is a mother fucker.