1999 Nissan Sentra Struts

1999 Nissan Sentra 4 cyl Two Wheel Drive Automatic

I recently had my car into the shop and they told me I need to replace the struts as soon as possible. I thought they said I needed to save up about $900.00 for this. When I went online, it looked like the part less than $100.00. Does it really cost a lot to replace and repair the struts? My car isn't worth much money and I have already put about $2,000 into it in the past 90 days.