Well, they aren't terribly hard to handle...at least stenophrys. I can only say I'd recommend starting with L. stenophrys as they are the least sensitive to stress and you can purchase Cb babies that are already eating. I would stay away from WC Lachesis of any kind until you have more experience with them. Only a handful of WC ever survive, and most that are imported are roughly handled in the process.
L. muta is more nervous and L. melanocephala can be a bear to deal with (and the hybrids of steno x melanocepala....they are another story.)
THey simply have specific requirments to ensure proper health. You can't simply throw them in a cage and expect them to thrive as say with a rattlesnake (oh they may survive, but not thrive to the point where they'll breed). Also, there are some diseases like "pink belly" that they will be susceptible to, and may kill a snake with few external signs.
So it's not really a snake that's tough to deal from a handling standpoint, they just need the right environment....including A HUGE CAGE. The bigger the better. I keep adults in 8' x 4' x 3' enclosures....and I think that's a bare minimum for keeping them successfully. They require HIGH humidity BUT NOT WET SUBSTRATE or they will get the Pink belly disease.
As for Gaboon Keepers post below...$1700 is iffy, usually $2500 is the norm for Melanocephala. If and when Ripa or Randall have stenophrys babies they are $1200. Muta babies are not much cheaper. I imported 3 cbb Costa Rican babies last year but would probably have asked more for them since they were unrelated animals to Ripa or Berry animals, but they are not for sale (In fact a female was so stressed by the shipping that she died several days after arrival--the males are not 3' ).
Matt