I too was hunting the "holy grail" c99 recently and wound up with peakseedsbc and fleur du mal (fdmseeds.com). I knew I wanted peak's based on consistent reviews but it was a fluke that I picked up FDM's. I found them on an overgrow thread and sounded legit, but I thought they were based in UK or France based on the name. A little more searching and behold... right up the road from me in Sonoma County California. That sealed it for me so I sent an email to check the vybe on the response, which was all good to me. I wound up with their C99, General's Daughter (G13xC99), and both mix packs they offer: "?"xC99, and "?"xDurban. I sent cash in an envelope and completely happy with the goods I got. Packaging was a solid A+ and did not seem cheesy at all... official gear for sure. Looking forward to flowering in a few months.
uJhiteLiger: I'm sure "back crossed" does not mean "crossed" with something else. I take it to mean he flowered "original Bros Grimm" stock, selected males and females from the offspring based on desired traits (frost, smell, flowering speed, etc), and "back crossed" (bred males and females with desired qualities) to produce more of the same traits in those offspring. Someone correct me if I'm wrong. Bottom line is his C99 line is from original Bros Grimm seeds and that's why I chose them.
thenotsoesoteric: I read somewhere that Peak's C99 is from Frost Brothers, not Brothers Grimm. Here's the reference: "From what I understand he has been working on the C99 for a while but the SS x C99 is new. The story of how he obtained the c99 can be found on the TY forums. He told me he has added 3 generations onto the C99 since receiving the Frost Bros C99(Bros Grimm f4), which would make them f7's. The uniformity is stunning." That quote is from 2015.
Oh I should add that both Peak and FDM have stuff that's not listed on their website menus. Email them first and ask.
One last thing... I grabbed one of the last packs of Bros Grimm C99xDurban ("not" their C99xDurban/Thai which is only feminized). This DC99 is regular and hasn't been available in years from Bros Grimm. I snagged them from HeWp De Pot with some of Joey's AK-47. I don't know why I didn't grab his C99, but I think its similar to Peak's. I'll grab some of Joey's C99 on my next order from them and run all three next year.
LH