dinjo said:
Its the buyer who decides who he wants to sell, not the price.
You are right that the seller decides whom he wants to sell, but in practice generally the item is sold to the person who responds first with preference being given to a local buyer at any stage of the transaction.
In this case as both buyers were local, in all fairness you should have sold it to the person who pmed you first
If for some reason you have not sold it to him a personal PM giving the reason for the same would have gone a long way in soothing the ruffled feathers instead of the curt reply given by you IMO