Is demand always so high for cheap Grendel ammo? Yep. Manufacturers haven't figured out how much of a market there is for Grendel, yet.
Get on the notice list for Sportsmans Warehouse for their American Gunner ammo. It is $140 for 200 rounds BTHP, shipped. When it comes in stock, they will send you a note. Order quick. It is good stuff. It shoots very close to the same POI out of my rifle as my Hornady SST 123 gr. hunting ammo.
Following loguon, I would say that there are much better and/or more common calibers that I would shoot through a bolt action than Grendel. Grendel is sort of topped out for the AR15 and if you aren't already shooting it in your AR15 (which I do and really like it), then why go the Grendel route for a bolt action?