well it really depends, yes there are people who wont trade for lowend stuff but there are also plenty that will, me ive moved a good amount of base to set builders for one or two base rookie cards, it really all depends on what your trying to trade and wht your expecting in return. i tend to go for somewhat equal total bv, some will go off of the potential value of one card for the established value of another, and then you'll have team/player collectors that are willing to take one on the chin so to speak in order to get cards they really want.
I personally think sticking to equal bv is a good way to trade, but be flexible to, never ask for more than youd be willing to give up, put yourself in the other persons shoes, and be realistic with what you have and you should be able to find someone who will trade with you.