Depending on what you desire the whips for, one of the more economical choices are to buy a venomthrope, 4 whips included, sized for warrioirs and tyrant guard, and then i turned around and used the body /head for a Doom of Mal conversion.Monstrous whips can be esily converted from the feeder tube from venom cannon from the older hive tyrant/carnifex sets . Another usally more expensive but less labor intensive is ebay (cough cough) . Certain dealers like "battlewagon bits" take entire sets and sell off individual parts,make sure to try and take advantage of mutiple bids to get breaks on shipping to help make worthwhile.
There are old skydivers and there are bold skydivers,but there are no bold,old skydivers.