In the US:
Amazon - Savings on PC gaming components
Walmart - Some good savings on RAM
Best Buy - Decent deals on Corsair DDR4 and DDR5 RAM
Staples - Discounts on memory for laptops and desktops
In the UK:
Amazon - Savings on PC DDR4 and DDR5 memory
Ebuyer - Great deals on PC gaming memory
Overclockers - Big savings on Team, Kingston and Corsair RAM
Scan - Hundreds of RAM models to choose from