Buying a new 27-inch iMac? Here's how to save hundreds - even thousands - of dollars

Don't make this mistake that Apple wants you to make.

There's nothing like buying a new Mac to put a hole in your bank account. In the space of a few clicks, you've put a machine in your shopping cart with a price tag that makes your eyes fly open.

Sure, Macs are expensive, but don't make this mistake.

What mistake is that?

Buying the RAM upgrade from Apple.

Must read: Does this accessory damage your MacBook?

The new 27-inch iMac comes with a base memory configuration of 8GB. For a desktop Mac this is acceptable, but 16GB gives things like Google Chrome extra breathing space.

And Apple knows this, which is why it made this decision, and made the 16GB upgrade a whopping $200.

$200 for RAM that costs about $65 from Newegg. Add this to your new 8GB iMac and you have 24GB for the fraction of the cost. In fact, you can get 32GB (two 16GB modules) from Newegg for $105, which would give you a Mac with 40GB.

128GB of RAM from Apple adds an incredible $2,600 to the price. You can add this yourself for $850.

And it's not hard to do. Apple even has instructions for you on how to do it.