I found some Federal magnum primers at the local gun show over the weekend. $13 for a tray of 100. High but not bad for these times. I had recently bought 200 Win magnum primers from a fella at the trap club for $25. I now have enough to last me forever at the rate I shoot my 404.
For comparison, two years ago I ordered 200 Federal Gold large rifle (NOT magnum) primers online from the only place in Canada that had ANY primers, Italian Sports in Vancouver. By the time the two trays were to my door it cost me $200 almost to the penny!!
My advice is don't get in a hurry. Availability of components and ammo seems to be improving daily = prices are dropping fast. I'm seeing a bunch of online vendors suddenly selling 404 factory Hornady ammo the last couple weeks and as low as $135 per box. A couple months ago you couldn't find the same stuff online anywhere and if you did turn up the odd box, it was $200 or more (usually out of stock the next day). Look for deals coming up on internet auction sites and at gunshows. The hoarders will be trying to unload before they have to absorb their losses. Remember what it was like a year after Obama was elected? Man, there were bargains to be had everywhere when that silly panic finished running its course.