What is the per-participant cost in a five-person group buy once testing is included?

I am comparing three suppliers on documentation rather than on price.

I have worked this out and I would like someone to find the error, because I suspect there is one.

My working so far, for the record, is below, and I am fairly sure the error is in the unit conversion rather than the algebra.

Is my approach right even if my number is wrong?

Start with how the material is split, because a shipment divided after arrival introduces a handling step that no certificate covers.

Splitting sealed vials preserves the manufacturer's container closure and the lot traceability. Splitting anything that has been opened, reconstituted or repackaged breaks both and no certificate follows the material after that point.

Certificate red flags and what each implies

Put another way, onward distribution — even at cost, even among people who paid — may be a different legal act from personal importation in many jurisdictions. It is worth understanding the local position rather than assuming.

Nothing here is legal or medical advice, and research-use compounds are not approved for human use.

Start small even with several people. Especially with several people.

Answering this needs to know whether the split is of sealed vials or of anything opened, since those are different situations entirely.

Custody is the risk. One person holds the money before the order and the material after it, and there is no mechanism to compel anything if it goes wrong.

Whoever receives the consignment is the importer of record in most jurisdictions, regardless of who paid. That is a legal position rather than an administrative one and it does not divide among contributors.

Splitting opened or reconstituted material is a manufacturing step performed outside any controlled environment.

Write down who paid what and who received what, before it ships.

edited 18 Feb 2026 by kwn_analytical — clarified the distinction between purity and content

In practice, a single lot across the group is the one genuine analytical advantage, because everyone's vial is then covered by the same test.

Ordering a single lot for the whole group is the analytical advantage: one independent submission then characterises everyone's material, which spreads the cost of testing across the participants.

Put another way, a first group order should be small for the same reason a first individual order should be, and the argument is stronger rather than weaker when several people are exposed.

Importer-of-record status attaches to the receiving party in most customs regimes and is not divisible among contributors.

One lot for the group means one submission covers everybody. That is the real advantage.

Concretely, this is one of the areas where the practical advice is mostly about structure rather than about chemistry.

The real saving is in carriage and in unit price breaks, not in the compound itself. Carriage on a single larger consignment is typically a fraction of the sum of individual shipments, and that is where most of the arithmetic comes from.

A single lot across all participants means one independent submission characterises the whole consignment, which is the strongest analytical argument for the arrangement.

Split sealed vials only. Anything else breaks the certificate and the closure together.

The short version: real savings on carriage and unit price, real risks in custody, splitting and the legal position of whoever receives it.

Keep a written record: who contributed, what was ordered, which lot arrived, how many vials each person received and when. It resolves disputes and it is the only documentation that will exist.

Whoever receives it is the importer. Make sure that person knows.