It is a situation where a salesperson announces to a group of people to attract them to buy his goods.
Here is the full sentence:
しかもおねだんは半{はん}額{がく}以{い}下{か}ときている
It is a situation where a salesperson announces to a group of people to attract them to buy his goods.
Here is the full sentence:
しかもおねだんは半{はん}額{がく}以{い}下{か}ときている
Here, と + 来る is an idiomatic expression.
The デジタル大辞泉 entry says:
6 (「…ときたら」「…ときては」「…とくると」などの形で)ある物事を特に取り上げ強調して言う意を表す。特に…の場合は。…について言うと。「酒とくると、からっきしだめだ」「甘い物ときたら、目がない」
which roughly means "used to focus on and emphasize a particular matter; when it comes to; as for".
While the examples above don't perfectly match your case, you can get the spirit and translate it like:
...and what's more, you know what, it's more than 50% off!
Note
I have to say that I'm not completely satisfied with the dictionary definition I cited, but I couldn't find any other reliable sources. In my view, "とくる followed by conditional" and "independent とくる" are different, and the latter is used to point out the surprise when some event strikes you in an unexpected way.
To answer without looking at or copying from anything,
「しかも~~~ときている」 means "On top of all that, it comes with ~~~."
This is an exclamatory expression or at least one of surprise.
It is difficult to translate 「ときている」 all by itself (and it is not often used by itself, either).
There would have to be other "advantages" mentioned in the immediate context besides the over-50% discount.
Edit: In case you are wondering, I did not use the phrase "to come with" in my translation because the original phrase contains 「ときている」. It is just a coincidence and I did not even notice it when I first posted my answer an hour or two ago.
It actually is "to kiteiru" not tokiteiru. The salesman is trying to say that the sale is upcoming. This website provides a nice response: http://detail.chiebukuro.yahoo.co.jp/qa/question_detail/q1144370201
"漢字表現をどうしても当てはめるなら「来ている」になりますが、 補助的な意味ですので、ひらがなで書いた方が望ましいかと思います。"
Perhaps rewriting the sentence could be elucidating:
"しかもお値段は半額以下と来ている"
What's more! The Price will be lower than Half Price! Coming soon! (English vers)