I don't know where you live, but in the US stores like Ross Dress for Less(basically a store that gets cheap surplus/leftover stock, primarily clothes, as well as budget brand stuff) and Dollar General sometimes stock newer versions of the Doubleshot, a double barrel shotgun from the same brand that uses the same shells. Saw a few last time I went a couple weeks ago. Also there's occasionally a variant called Rick's Shotgun. I would start looking for those blasters if you can't find a person who can 3D print locally.

Additionally, from my experience, last generation Zuru X-shot darts(flat pancake head) are almost a perfect legacy Buzzbee dart option. Shorter length, wide holes, and widely available cheap blasters often come with a ton of them.