Indeed! The 'Mega Rare' pieces are the ones you didn't mention-the 30 backs!!!
By all accounts I hear some jammy novice got those!!
Hansons hammer prices for some factory sealed Palitoy 12 and 20 backs 29th Sept;
12 back DSC £420
12 back stromtrooper £380
12 back Ben £1050
20 back Luke X-Wing £420
20 back R5-D4 £240
20 back Walrus £360
20 back Death Star Droid(not earth Star Droid) £550
20 back Power Droid £300
Please be aware the auction house gave crap info on condition of these piece so unless one was there, one wouldn't have had much of a clue!
Assuming they were mint, prices are on the low side some very low ie R5-D4, Power Doid. Walrus Man was fairly low too!