>>3083382Nendoroids are designed as collector's items, and created and sold in batches. Because of this it's best to pre-order anything you want, otherwise you have to deal with the aftermarket, which can get pretty shitty in some cases. I don't know if Holo will be reissued, but I'd wager it's unlikely unless they make a second S&W nendo, or a Wolf and Parchment anime gets crazy levels of popularity.
You can keep and eye out on import sites like Amiami and see if a figure pops up either new or pre-owned; I'd recommend this for minimal hassle.
You can also get her right now on Amazon, but the price is jacked up to about $74 right now. For comparison, price on release was like 4800 yen plus shipping, which comes out to about $60 in total. If you do use Amazon, check to make sure the seller is from the US or Japan; if you order from China there's a much higher chance you're getting a bootleg.
I hope this helps.