Glad I did not buy a new Mac! Good as new!
This is a 2.8ghz Intel i7 21.5 inch IMac from Mid 2011. Pretty old, right? It was VERY VERY VERY slow. Even with a fresh operating system install, it was barely usable. We spent this small amount of money upgrading from a 2TB HDD to a 1TB SSD. Notice the before and after pictures. We wanted to use this computer as the family computer -- but now it's a fully capable workstation for my wife's work and my kids work. I bought this originally for my business and my wife's work. However, about 5 years ago, it became too slow. I wish I upgraded it sooner.
The repair was a moderately difficulty repair. The most difficult part is the very short-tethered LCD display cable. It is VERY VERY VERY fragile and the connection is almost impossible to feel with your hand. Accordingly, even after putting the machine back together, I was not sure the cable was properly inserted until I powered the machine back on and the screen worked. I think the guide in this should have put a giant red box around this part of the repair and attached a video instructing how to do this part. VERY difficult. Everything else was simply time consuming.
Buy the toolkit that comes with most of these SSD upgrades. You'll need the whole kit. Also, make sure you have a can of air nearby as the inside of the unit is most likely VERY dusty. Also, consider maxing out the possible memory of the device. Being that I was this deep into the unit, I wish I replaced the DVD drive that has been giving us trouble -- as it would have been a minor additional effort. THIS IS AN AMAZING UPGRADE and almost made the computer good as new. The only drawback is that because of the age of the unit, I cannot install anything past OS X High Sierra.