The answer is a resounding no.
Regardless of its actual Ballistic Skill, a model without ranged weapons has an effective Ballistic Skill of 0. A hormagaunt with BS 10 will cost no more or less than a normal hormagaunt. Add any ranged weapon to its outfit and then the cost of the model will skyrocket.
Why Ballistic skill and not anything else? Because no other stat can be ignored with the exception of specific rules. Your WS/S/T/I/W/Ld/Sv are all going to be referenced at some point. Whether or not those stats are effective is a different matter entirely.