Trunk wont stay open

[Houli715]

I have a Nissan 240SX SE convertible that is 16 years old. I purchased it from a previous owner two years ago and it is in good condition. There are really only minor problems with it, all cosmetic related. It runs great. The trunk actually will not stay open on its own. The shocks that are supposed to keep it suspended in the air upon opening must be broken- it rarely will hold its own for me. I most likely need to replace them entirely. I am wondering how much they run? It is a hassle to hold the trunk open while I am trying load and unload it- it is heavy and hurts when it falls down on me.