That's unreasonable! I'd take it for (100￥.)
这真是卖得太贵了！如果（一百块）我就买。

How about (100￥)?
卖（一百块钱）如何？

I'd buy this if it were cheaper.
再便宜一点我就买。

Lower the price, and I'll consider it.
价钱低一点我才会考虑。

It's a little overpriced.
这标价有点贵。

I like everything about it except the price.
这东西除了价钱之外我都喜欢。

I've seen this cheaper (in) other places.
我在别家有看过更便宜的。

I heard other stores were having great mark－downs on this item.
听说别家的这个东西在大减价。

If I buy more than one, will you give me a discount?
多买一点有折扣吗？