TLDR: PeterTheGreat's 4-FIBF is an excellent value at just $50/gram, making it by far the best value US domestic fent product, and even competitive with bulk pricing that comes from China due to the higher quality.
I've already written what is probably the most comprehensive review of 4-FIBF overall, which you can find on bluelight (reply #22) and reddit.
So when I wrote my first reviews, I had only had one single source, it came from China and cost me $130 for a gram, and the vendor no longer carries it. When I tried other suppliers, I was able to get better prices, but I noticed the product was very different, in most cases much weaker. So I'll go through and detail my experiences so you can try and decide before you make a 4-FIBF purchase if you're going to get the strong stuff, the weak stuff, or something in between.
First Supplier (China - no longer available) - The first supplier shipped from China and cost me a lot compared to the others at $130 for 1 gram. Although it was the most expensive, it was a lot stronger than future orders. Most importantly, it came as a powder, it was a white powder, a little bit clumpy but not too terribly clumpy. My detailed reviews of 4-FIBF (links above) are based on this supplier, so it may paint it as a better analog than it might be if you get from a supplier with a weaker product. If you're like me you use your fent analogs with a nasal spray, so water solubility is important. This product had no problems with water solubility, so as long as you're using reasonable dosages, which is around 1mg/mL in my experience, you shouldn't have any problems just using distilled water to make your nasal sprays.
2nd & 3rd Supplier (China) - Both of these also shipped from China, and the product was absolutely the exact same product. it came as crystals, which is how you can know for sure you have the weaker stuff. If you're using the Tor browser and have an Alpha Bay account you can see an accurate picture of the weaker version here being sold by RcQueen. It may be appealing because RcQueen sells it for ~$25/gram, which is a hell of a lot cheaper than my original source, but the product is substantially weaker. From having experience with both, the actual effects are very similar if not the exact same, but in order to get the same feeling the dosage needed to be about 4x as high. So if you consider it about 1/4th as potent, it ends up being about the same as $100/gram. If you make nasal sprays, water solubility is particularly important with this form of 4-FIBF. Once you get around 0.5mg/mL using distilled water, the water starts to saturate and you get a very cloudy/thick solution that is difficult to push through a nasal sprayer. It can work short term, but you may need to replace your Nasal Sprayer nozzle more often. I found you can remedy this by using a solution of about 5% Propylene Glycol (PG) and 95% Distilled water. Adding salt only makes it worse. With 5% PG you wont really notice the PG other than maybe a vaguely sweet taste, but otherwise wont make a big difference other than making it more soluble. If you need to, you can add more PG, but larger portions of PG will eventually start to sting. So all in all, the prices make the value pretty similar, but you may need to buy some PG if you don't already have it to prepare your solutions with this stuff.
4th Supplier - PeterTheGreat (US) - I was skeptical when I saw a vendor selling 4-FIBF domestically at just $50/gram, expecting that it must be the same as the cheaper stuff I got from my 2nd & 3rd Chinese Suppliers, but on the off-chance it was more like the first supplier, I went out on a limb to try it, after all, having a domestic supplier is very useful. When I received it, I was pleasantly suprised to see it come in the form of white powder, very similar to the first supplier. It is also somewhat clumpy, perhaps even more clumpy than the original source, as parts of it actually compressed into small rocks. I can't tell if this is more clumpy than the first because the rocks crumble and it was sent in a 1" x 1" bag whereas the gram I got from my original supplier was in a 6" x 3" bag so any potential pebbles/clumps had a lot more space to spread out into and be crushed by mail sorting machines. I have a hard time saying it is exactly as strong as my original supplier which charged $130/gram, but it is definitely at least 2.5-3x stronger than the 2nd & 3rd Chinese supplier, so it's definitely stronger than the bulk stuff that comes out of China, making it a very good value at just $50/g. Similarly, it matches the first product in water solubility, so no need for PG to make the product more water soluble. Overall, I was very impressed with the product, plus it arrived just 2 days after I placed my order so it beats any order coming from China in terms of both speed and security by miles.
So what exactly causes these differences? It's hard to say for sure, I've asked around and nobody seems to be able to tell exactly, but my best guess is that it's a difference in the salt. For example when you compare Fentanyl Hcl vs Fentanyl Citrate, Fentanyl Hcl is roughly 10% stronger because the "Hcl" component is lighter than the "Citrate" component. Besides just having differences in weights, different salts can affect the form of the product and things like water solubility. Hcl is often chosen because it makes most things easily soluble in water. PeterTheGreat sells "4-FIBF Maleate", where Maleate is the important term there. Everyone else just sold plain "4-FIBF", so it was either a freebase (meaning no salt, so like 4-FIBF vs 4-FIBF Hcl), which is often more difficult to consume, might have lower bioavailability, etc, or it was a different salt from Maleate.
TLDR: PeterTheGreat's 4-FIBF is an excellent value at just $50/gram, making it by far the best value US domestic fent product, and even competitive with bulk pricing that comes from China due to the higher quality.
Is it true that the effects for 4-FIBF last much longer than any other fentalog on the market (previously and past)? I hear it's roughly 4-6 hours as opposed to one or two hours. I'm extremely interested in this chem. And haven't been able to find a cn vendor anywhere.