How much will a rear supsension spring cost for my opel astra 96?

Could a second hand one be used??|||Do not purchase a used or second hand one as it could sag and you will not be able to tell until you put it on, besides a brand new one will only cost around 20 gbp go for a good quality oe manufactor like lesjofors, boge or kilen i recommend probably replacing both because if one has gone its more than likely to go soon on the other side and you might as weel make 1 job of it.