其实and 并列的两个成分是the cheapest 和 the best.而on this earth作为状语可以放在句子的最后.
我们可以把句子省略的成分补上来,使句子变成:
It is the cheapest kind of medicine (that)there is and it is one of the best medicine (that)there is on this earth.
避免累赘和重复,可以进一步修改为:
It is the cheapest kind of medicine and one of the best there is on this earth.
It is ...there is和There is .意思一样,句形可以相互转换,只是后者比较常见,也用的比较普遍.所以我们最终可以把句子修改为:
There is the cheapest kind of medicine and one of the best on this earth.
翻译:这是地球上最便宜的一种药,也是最好的药之一.