It's more convenient and the price is usually cheaper than that in some big shopping malls.

price 比拟不必贵与廉价，要用低 low和高high，所以把cheaper改为lower就可以了。

在than和some之间加上that in（或许of）就行了，这句话想说这儿的价钱比某些大卖场的价钱还廉价，that指代price