Disclosure: We earn a commission from vendors on this page. Rankings are based on objective criteria including price, COA availability, and reputation.
Best P-21 Vendors of 2026
Ranked by Price, Purity, and Reputation
Currently out of stock. Every vendor we track for P-21is sold out right now. The vendors and pricing below are who normally carries it — links go to their product pages, where you can check availability or back-order. Use the notify form below to get an alert when it's back in stock.
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Quick Comparison
| Rank | Vendor | COA | Score | Doses |
|---|---|---|---|---|
| 1 | Swiss ChemsShips Worldwide | Yes | 10/10 |
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How We Score Vendors
Our scoring is based on three weighted factors:
Price Competitiveness (40%)
Normalized to cost per milligram for fair comparisons across vial sizes.
COA Availability (30%)
Third-party lab testing confirming purity, identity, and absence of contaminants.
Vendor Reputation (30%)
Community feedback, shipping reliability, customer service, and business track record.