Mate paid £68 for set of 4 normal shoes and when horse had egg bars in front and standard behind it went up to £120, so presume from that that she would have paid £34 for hinds only with normal shoes so £120 less £34 = £86 for 2 eggbars (that is of course if my maths is correct this morning!)
Well I would expect to pay around 30 for a pair of regular shoes, plus maybe 10 to trim the backs.
I can't remember off the top of my head what it cost me when an old horse was in eggbars but I would imagine an extra £10-20 a foot.
So would hazard a guesstimate at approximately £70 to shoe the fronts in eggbars and trim the backs.