Have you already got the work lined up? Someone in the business section may correct me on this, most low end estate agents seem to take their own photos with compact cameras (they did with the houses I bought/sold, photos good enough for rightmove can be taken quite easily and quickly whilst measuring up and taking the description details). Estate agents selling top end houses may pay out for photography and probably have photographers to do it organised already. It would be worth lining up the work before spending on a lens if the only reason to purchase is for paid estate agency work. That said you may need a portfolio of images to show what you can offer them is worth them paying you to do it for them and better than they can do themselves. It may also be worth offering the measuring and description detail service too otherwise it's an addition visit for the seller, that would be a key point for me as a seller, the less visits the better.
