Listings plugin?

Hi,

I have been asked by a client to build a site. A small part of it will be content-managed(special offers, events etc.), but they also want to be able to add and edit Property for sale(so you’d have a few thumbnails linking to larger pics, description, price, viewing, pdf download etc.)

How would you suggest I approach this?

Should I build something from scratch, or is there a plugin similar to this for WordPress already, that I could just tweak?

I have built something similar before(separate to WP) – would it be easy to incorporate into WordPress, or does it depend?

Many thanks for any advice.