https://www.gunandgame.com/threads/looking-for-savage-250-3000-ammo.147668/
Man, I wish I would have read your second post in this thread correctly, I just spent a ton of time trying not to disappoint this little girl's (young woman?) hunt.
At least you might be able to use this information going forward.
I searched many, many sites and only came up with a few options.
1. Reloading. You're going to need to do it anyways eventually with this cartridge.
2. Gunbroker. I saw a few auctions available ending in a day or two. No doubt you'll probably have to pay a premium.
3. Try checking a few of the lesser known gun boutiques. You never know. Also try contacting any LGS in a radius you're comfortable with and see if they have any available or know anyone.
Don't forget to mention that you don't want to let down your daughter. Heck the thought of it hooked me
4. & the bottom of the barrel. The link above has a poster at the bottom of the page offering to sell some rounds a few months back. He left his email address incase you want to contact him.
I hope the season fares well for you and your daughter. Best of luck to both of you & be safe!