With the way scales are made today and the fact that most of them are guaranteed to be within tolerance for life, I think any cheap new scale should suffice. As far as records are concerned, I seriously doubt you'll ever have a person who would bring a gun right at the limit, shoot well enough to worry about it. Those types don't generally do so well. For the ones who are way over the limit, who would care, just dq em.
The cost of a set of standards seems like a waste to me. Even to take a bowl full of concrete and have that certified is a waste. Ask all the people who have scales with .01# resolution and I bet you'll find they weigh in exactly on what the certified scales do, (if they ever get to use such a thing).
If the Nbrsa requires the use of some set of standards, then I'd suggest they supply them to the clubs for free. I mean, you can go to places where they've spent all this time writing rules and all, then never put the guns on scales anyhow.
Test weights will cost WAY more than the scale.