This model of Apple iMac seems to sell for about $500 currently.
In 2011 this iMac shipped with a measly 4GB of RAM and there’s four slots to use so you could add another 4GB to get to 8GB, or add 3 of them to the original 4GB to get to 16 GB. I don’t really see a need for 32GB in this model as the RAM could cost as much as the computer, but the option is there if need be.
You are better off taking the money you saved on buying just 16GB of RAM for this iMac and upgrading the hard drive to an SSD. Popular and affordable sizes of SSD’s are 250GB or 500GB. You can upgrade to a 1TB model but it’s pretty pricey still.
This iMac still has a lot of life yet even though it’s starting to show it’s age. Spend about $200 on the RAM and SSD upgrades and this will increase performance considerably compared to the original specifications on the release date.
image credit: Amazon