Today I completed all of my four 1992 10p varieties with the rarest one turning up in my change from Greggs! The rarest one is quite worn though. I will keep my eyes open for a better example.
Best Buy: 1924 BU Gem halfpenny bought for £22 worth about £35 in this gem mint state with blazing lustre! Worst Buy: 1896LX Crown VF bought for £40, sold to a dealer a while ago for £16.
How about a nice 1903 BU GEM half penny?! All joking aside, a beutifully UNC coin will have to be on the cover devoid of surface marks or pitting to attract the numismatic eye.
My dad is trying to do the same thing, but with high grade examples with full or almost full lustre. I am looking out for high grade coins especially bronze or copper for his portfolio.