能省多少钱？

我也很想求一个。

顺便请教个问题。 我买的costco的king 床，
网页上写到：
King Bed Features:

High, curved sleigh headboard with and sleigh footboard
Solid hardwood frame
Strong metal brackets
13 slats with support legs
Mattress and box spring not included (box spring not required)

我听说使用box sping 对床垫有好处。如果我买床垫时顺便买box sping，应该买哪种呢？