Tigrina is way up there, theres Tons of pikes though and many get confused with one another untill they are all identified its nearly impossible to tell you which is the rareist
C. rosemarie is definitely one of the rarer/most expensive pikes. My guess is they would cost more then tigrina, which go for about $1500, as I don't think they have been kept in captivity (maybe in Japan, but even then, very few)and are WAY more attractive.
Cobras are seasonal and readily available. Celidochilus are very rare and occationally available (I still have a few for sale) tigieina are never available and with the way Brazil has gotten, may never be. Ken