Welcome to the family.....I am based in the UK and have about 20 C versi slings available (plus a new sac) so feel free to message me when ready and if you need any more info on care needs.U have convinced me lol will have to add it to my shopping basket
C. versicolor require a somewhat humid environment but you must have plenty of cross ventilation to prevent stagnant air and mold. Keep your substrate slightly damp (not soaked) and provide a reservoir. Other than that, they are fairly hardy arboreals.
Not to come off as a correction, I would not keep C. versi in a humid environment, but like Casey said, cross ventilation and slightly higher than relative humidity can be accomplished by simply my over flowing the water dish once every week or so - the more substrate you have the more moisture it will hold for longer. This, combined with good cross ventilation, will create ample humidity for an avicularia sp.