I've always felt like this was the most critical element personally.
Cost has never made me outright cancel a trip to the range, necessarily. I've been broke from time to time, but never that broke. But sometimes finances have been an occasional nagging voice in the back of my head.
It's nice to nip that problem before it even starts, and pick a common caliber to practice with and buy a shitton of it in bulk (before the next manufactured panic spikes ammo prices).
I'm sure it's far, far more valuable to be more practiced with a less effective round than to have a slightly more technically capable round and be a bumbling fuckup when shooting it.
I've been wanting to buy a 357 revolver for months now. I keep going to Nation's Gun Show outside of DC, wistfully eyeing the revolvers, and going home empty handed.
I think I'm going to nut up and buy something next time.