I honestly think something like this would be better sold at a car boot as there doesn't seem to be much vintage these days at them, and when people see stuff like this they often think it's worth slot more than what your asking, just my thoughts
I feel that you would get more than 70 GBP if sold separately on ebay and it might be worth looking into the cost of getting some guns for the x-wings and selling them complete. That may end up not being worth while but maybe worth looking into anyway.