Being able to visit three countries for almost the same price is a good deal!
Almost the same price=価格がほぼ同じ→そんなに変わらない値段
good deal=お得
That's a good deal that you can visit three countries for almost the price of one!
1か国行くのと同じような価格で3か国いけるなんてお得だね!
と表現する方法もあると思います。