She diidn't want to buy it, _____

让步状语从句部分倒装.
引导让步状语从句的连词主要有以下这些：though, although, as; even if, even though; whether...or...; no matter+疑问词，疑问词-ever。
however good it was 这里However即疑问词-ever，被倒装的部分是表语good.

其它例句：
However (=No matter how) expensive it may be, I’ll take it.无论它有多贵，我也要买下它。
Don’t let them in, whoever(=no matter who) they are.不管他们是谁，别让他们进来。

however是连词，引导的是让步状语从句，要放在句首。因为how是个副词，它后面要跟形容词或其他副词，并且，句子的语序要用陈述语序。。

however good it was是指“不管它有多好”，however在这里也就是 no matter how

however good it was 是无论它有多好的意思～