Why do prices for the same peptide vary so much between sellers?

Mostly vial size and testing overhead, not necessarily quality. On this site's pricing data, tirzepatide has run from about $1.14 to $12.75 per milligram across sellers, and semaglutide from about $1.50 to $34 per milligram, even holding vial size constant in some comparisons. A vendor that pays for independent lab testing on every batch has a real cost a vendor that does not has skipped, which is one honest reason the cheapest listing is not always the same product.

Educational use only. This database summarizes published research and is not medical advice. Where a dose appears it is a record of what a trial or clinic ran, or what people describe doing, with its source attached. Nothing here is a recommendation for personal use.

Part of buying, vendors, and lab testing. How to evaluate a seller's claims, certificates of analysis, and pricing.