A store who accepts bitcoin knows what they are doing, it is their responsibility to accept either it will drop or not. As long as they’ve established their mode of payment and accepting bitcoins gives you an opportunity to make a fast transaction. By using bitcoin as payment also gives the store an attraction to the consumers who holds bitcoin because they will think they can save more just by using bitcoin.
Hopefully, the story from @OP can inspire other shops to start accepting payments using bitcoin so that it will make the spread of bitcoin even better. And hopefully, the government can see this so they won't think that bitcoin is just a tool for illegal activities. Maybe @OP can convert right away after receiving his bitcoins so he can still make a profit. Or if @OP can hold his bitcoin for a while until the price goes up again, he will sell his bitcoin so that the profit can be bigger.