Where to purchase additional memory from?

North45j wrote:

I’m confused. Just earlier today I spoke to Apple and the support person I talked to said that I could install another 8GB of memory by myself

.

If it is an iMac (24-inch, M1, 2021) like you said, you cannot.

Jack

The RAM is not upgradeable in a 24" M1 based iMacs. So the answer to your question is "nowhere."

You were advised incorrectly, the earlier 24" iMacs (pre 2011) had upgradeable RAM, your M1 based iMac does not.

Your welcome, if your iMac is 2 weeks old or less and you bought it from Apple then return it and order with 16GB of RAM and the largest SSD you can afford.

Welcome to the Apple Support Communities.

Sorry, you cannot upgrade the Memory on iMac (24-inch, M1, 2021).

Jack