Well,
I've done some asking around some UK manufacturers and the price comes in around this ball park:
100 x 18mm custom dice with 4 special faces and 2 blank faces - 1.20 GBP per dice
100 x 22mm custom dice with 4 special faces and 2 blank faces - 1.52 GBP per dice
Royal Mail 1st Class will be a maximum of 4.25 GBP for the 22mm dice
Then VAT at 15%
Lead time at the moment is approx 3 weeks
So about £175 for a hundred (25 sets of fudge dice at 4 dice to a set) which is a bit steep but for me that's only really enough for 4 sets (based on 1 for the gm and 5 players), I'm sure we can get more. Also they have cited what I asked for (+ & -) so having arcane symbol and skull may not be any more expensive.
If there were say 50 gms buying dice for their game say 5 sets on average that might make an interesting reduction to the cost though shipping round the world may make this idea null and void anyway.
But say if the following is met
People are prepared to pay up front but wait til 5 weeks before Origins for the order to go in (so order can be put in and shipped out so you have the dice in time for playing and hopefully more people can hear of it and add in orders to get the cost down more)
Choice is made on what the symbols would be (I think skull and star would be ok)
People are prepared to hand over say $15.00 per set to cover postage to cover purchase and shipping (with a return of any excess), I'm guessing the cost would come down a bit if we can up the order
then I'm happy to do the organising ;-)
Chris