what do you mean by fair? to you or the client? two very different things I guess based on you asking the question. I agree it sounds like the client is balking. How do you normally bill? if it was only 1 rental what would your fee be? then multiply it by the amount of work to do 4 plus the sale of the rental.

I'm in NYC and know what my fee would be for this return. If client doesn't like the fee, then they are welcome to find someone who would do it for less. If they are a long time client, I might be willing to "adjust" a little. Bill for your time and experience - don't shortchange yourself for the amount of time this would or could take you.