What SSD should I upgrade to?

I have a mid 2015 IMac and it’s starting to run pretty slow, is there a part I could upgrade preferably under 80$ that could make it better?

IMAC mid 2015 specs: 3.3 GHz Quad-Core Intel Core i5 24 GB 1600 MHz DDR3 AMD Radeon R9 M290 2 GB