I think that is correct. I can't see them allowing you to leave with whatever you bring so if you have a homemade or 3-D printed gun or 100 of them youre going to be sent on your way with $25 bucks and they will keep whatever you brought.
More likely relevant if the ATF were in charge of the buyback (of course they are not) and the website and flyer didn't say you'll get "$25 total" for anything printed or homemade. I've heard of people printing items and making great $$$$$ but it seems this is different.
The press release on...
The flyer I read said $25 TOTAL for a printed or homemade gun, whatever that is, so if you bring one printed pistol or 10 you get $25. That's at least how it reads to me. My gas would be more than that.