Hoping to go after elk for the first time so yeah, I picked up a 6.5 PRC.

I go to an indoor range so it really would be a waste

If I added a caliber, it would likely be one I didn't have to buy magazines for. I buy 15 magazines minimum for each firearm that uses detachable mags. Met a guy who had a drum fed 12g folks drooled over, but only 1 drum...he said when they came up for sale they were $600 used.

12g, all tube mags; .410 (lever action/ tube mag); .357 (revolver - just 2 speed loaders);

Detachable mags:
.22lr, 9mm, 10mm, .45ACP, .300BO, 5.56x45, 7.62x39

I divested of
.380ACP and 7.62x51/.308.

I intend to get a longer range bolt rifle, haven't decided which caliber, leaning to 6.5Creedmoor but .338LaPua, .300WMR, couple others in consideration but I can't even decide on caliber, let alone platform, and it would be highest cost/ least opportunity to shoot, so my budget has gone to suppressors mostly.

I'm thinking adding another suppressor would serve me better than adding a new caliber

Trade out the .380 for .308, add 7,62x39 and you’ll have exactly what I have for calibers after several consolidations.

Still plenty of shit out there for me to buy with my self-imposed limitation.

Currently I have 11 different calibers, and I don't envision getting rid of any of them. I could probably do without .357 and .22 magnum, but why would I? I would have already added a .357 mag lever gun, if those all weren't so stupidly overpriced the last 5 years or so.  

I do not have and have always wanted .45 Colt, and 45-70, so those are likely to be added in the future. I've always kinda considered a .460 or other big bore revolver. Banging steel with big bore is just fun. .50BMG has always been on the list and I just never got around to it yet.

So if you ask me, yeah I would add to that, somewhere around 15 calibers is about the right number.

Sure, I'll remove my only pocket pistol (only reason I have 380) for something I cannot use because indoor range...

What centerfire calibers do PSA/AAC make?  Stick with those for now.

You asked and I gave one of many answers.