Best P21 vendors in 2026
Buying P21: what the field looks like
We track 8 in-stock P21 listings across 6 US retail vendors, and re-read every one of them each night. Ranking below is by cost per milligram, which is the only figure that compares a 5mg vial against a 10mg one honestly.
The cheapest source works out at $4.17/mg against a median of $9.46/mg across the field — 56% less for the same milligram of the same compound. That gap is why this page exists: on P21 the vendor you pick matters more than the size you buy.
The lowest total cart is $49.99 at evolvebiopep. That is the cheapest way to hold P21 at all, which is a different question from the best cost per milligram — the two are the same vendor only sometimes.
Top 5 P21 vendors at a glance
| # | Vendor | Size | Cheapest vial | Per mg | vs median | Score | |
|---|---|---|---|---|---|---|---|
| 1 | evolvebiopep | 12mg | $49.99 | $4.17 | 56% under | 6.8/10 | View → |
| 2 | rescueresearchusa | 10mg | $89.99 | $9.00 | 5% under | 3.5/10 | View → |
| 3 | atomiklabz | 12mg | $119.00 | $9.92 | — | 6.1/10 | View → |
| 4 | solutionpeptides | 12mg | $119.00 | $9.92 | — | 5.8/10 | View → |
| 5 | alphaomegapeptide | 10mg | $198.00 | $19.80 | — | 4.7/10 | View → |
All 6 ranked P21 vendors
evolvebiopep
12mg$49.99$4.17/mg6.8/10Get deal →Prices sit in the 13th percentile of each compound's field — cheaper than 87% of listings. · Cheapest source we track on 11 compounds. · 34 compounds, 44 live listings. · 98% of listings in stock at the last check. · No certificates published that we could find. · Tracked for 2 days.
rescueresearchusa
10mg$89.99$9.00/mg3.5/10Get deal →Prices sit in the 54th percentile of each compound's field — cheaper than 46% of listings. · 10 compounds, 10 live listings. · 63% of listings in stock at the last check. · No certificates published that we could find. · Tracked for 2 days.
atomiklabz
12mg$119.00$9.92/mgpack: 10× → $8.93/mg6.1/10Get deal →Prices sit in the 47th percentile of each compound's field — cheaper than 53% of listings. · Cheapest source we track on 1 compound. · 52 compounds, 140 live listings. · 98% of listings in stock at the last check. · Certificates published on 1% of listings, newest 13 months old. · Tracked for 2 days.
solutionpeptides
12mg$119.00$9.92/mgpack: 10× → $8.93/mg5.8/10Get deal →Prices sit in the 53th percentile of each compound's field — cheaper than 47% of listings. · Cheapest source we track on 1 compound. · 52 compounds, 154 live listings. · 94% of listings in stock at the last check. · Certificates published on 3% of listings, newest 41 months old. · Tracked for 2 days.
alphaomegapeptide
10mg$198.00$19.80/mg4.7/10Get deal →Prices sit in the 61th percentile of each compound's field — cheaper than 39% of listings. · Cheapest source we track on 1 compound. · 28 compounds, 35 live listings. · 96% of listings in stock at the last check. · Certificates published on 9% of listings, newest 15 months old. · Tracked for 2 days.
libertypeptides
5mg$99.00$19.80/mg5.2/10Get deal →Prices sit in the 54th percentile of each compound's field — cheaper than 46% of listings. · Cheapest source we track on 4 compounds. · 37 compounds, 42 live listings. · 97% of listings in stock at the last check. · No certificates published that we could find. · Tracked for 2 days.
Bulk and multi-vial pricing
Ranked by cost per milligram. A pack is always a bigger cart than a single vial — the question these answer is whether it is cheaper per milligram, not whether it is cheaper.
P21 vial sizes compared
Vendors sell P21 in 3 sizes. Cost per milligram is not the same across them, so the biggest vial is not automatically the best value.
| Vial size | Vendors | Cheapest | Best per mg | At |
|---|---|---|---|---|
| 5mg | 1 | $99.00 | $19.80 | libertypeptides |
| 10mg | 2 | $89.99 | $9.00 | rescueresearchusa |
| 12mg | 3 | $49.99 | $4.17 | evolvebiopep |
P21 price history
Median cost per milligram across the field, one point per day we crawled.
How we rank these vendors
Vendors are ordered by cost per milligram of their cheapest in-stock single vial. Nothing else moves the order — not commission, not whether a vendor has a partner programme, not how long we have tracked them.
The score beside each vendor is a listing-quality score, not a purity or trust score. We have no laboratory and we do not test anything. It is built from figures we measure ourselves: where the vendor's prices sit inside each compound's own field, how many compounds they carry, how reliably their listings stay in stock, and how many certificates they publish. Every input is shown beside the number.
Prices older than 48 hours are dropped rather than shown stale, so a vendor missing from this page is usually a vendor whose site we could not read last night.
Common questions
Who sells P21 cheapest right now?
evolvebiopep, at $4.17 per milligram and $49.99 for the cheapest single vial. That is across 6 US retail vendors, checked within the last 24 hours.
How much should P21 cost per mg?
The median across 6 vendors is $9.46/mg. Anything at or under that is a fair price; the cheapest we can find is $4.17/mg, and the top of the market runs to $19.80/mg.
Which vial size of P21 is the best value?
Vendors sell P21 in 3 different vial sizes, and the cost per milligram is not the same across them. The table above prices each size separately so you can see which one is actually cheaper per mg rather than per vial.
Are multi-vial kits cheaper?
2 vendors sell P21 in multi-vial packs. They are usually cheaper per milligram and always a larger cart, so they are ranked separately above rather than mixed into the single-vial list.
Do you sell P21?
No. We sell nothing and ship nothing. Every link goes to the vendor's own store, and some of them pay us a commission — those are labelled on the row, and commission never affects the ranking, which sorts on price alone.