It is worth keeping an eye on local auctions. Boxes of Vicky pennies often come up in house clearance sales, and sometimes include some rarities unidentified.
The lower tiers of coin auctions can also be good as again they may not have identified the good ones. Also, you won't be fighting with the big bucks buyers. My local coin auction in Exeter, which runs every 3 weeks, has had some great pennies at low prices recently.