rough draft query

i sent a recent support email in relation to a header query. in light of this, because i’m not certain if a potential client is going to be happy with the result of what i am going to do for them, is it acceptable to do the following.

could i knock up a rough sample site using the enfold theme (as i have already purchased a regular licence for another site i am building) and then should they like the general look that i achieve i then purchase another separate regular licence for this client. just don’t want to really fork out to buy the licence again until i am certain they are 100% about going ahead as they will only give me the final go ahead once they have seen something they are suitably satisfied with and some of the things they are asking i’ve never done before and so until i try i’ve got no way of knowing if i can achieve what they want within the parameters of the enfold theme, and most likely the biggest parameter isn’t going to be your theme, but me myself and i lol! ;-)

please advise…

thanks,
paul