not so sure its sellers market now ...... most buyers holding fire with Brexit looming and the buy to let market stumbling due to Stamp duty and less willing lenders.
think about it, good local knowledge, good local staff,good local advertising etc etc........ House say £250k local agents at 1% £2500.....they are more likely to get closer to the asking price than purple bricks.
Unless of course you get lucky and many people want property then P bricks may do...