I would imagine that lots of people probably have their ashes scattered in the garden of house they have lived in for a long time. And that wouldn't bother me, but the thought of an actual body being buried in the garden, I wouldn't think too many people would be happy about that.
My dad is hanging on to my mum's ashes, and wants to be scattered with her, when he eventually dies (not in the garden), but if he wanted to be actually buried in the garden it would be a 'no way' from me!
I must say, I'm very surprised that burials are allowed in residential areas like this. Although, I could understand it, if it were some big old rambling property in the country, with large grounds.
I don't think many people will be interested in buying this property, regardless of the asking price, knowing that there's a body in the garden. Unless, perhaps, a landlord who wants to buy to rent, and not actually live there themselves ...