For a 12-year old car, if you have the original suspension components, then they are way overdue. I have done suspension work before but nowadays, just let the shop do it for me. It's a dangerous job, the springs in particular. So if you haven't done it before, just leave it to the pro. Each OEM strut, at a discounted from IoS costs $128. Depending on the number of parts to be replaced, it's going to be $500 or more.
If you have a friend who does suspension job, he can use the procedure from the Maxima/I30?I35 FAQ 'sticky'
zerothread/214767