Add average prices to property tiles

[adambricelis]

• Add average price to property tiles on front end
• Add supporting logic in back end

[adambricelis]

@ndrewh @maxdg99 this was a super cool feature from the hackathon but we kinda forgot about it

[ndrewh]

No u

[ndrewh]

Iirc I was shut down whenever i suggested how to incorporate this into the UI