Neo Geo games were expensive due to the expensive memory chips inside those plastic cartridges and they were heavy! They can hold up to 300 megabits, I don't remember exactly. Those were the technology back in the '90's though. Now, you can have 8 gigabytes of memory as a USB flash drive to plug in your computer...big difference there!
Do the math, most old video game cartridges memory are rated in megabits, not megabytes (gigabytes) which most computer geeks call them.
The number in megabits divided by 8 equals the answer in megabytes.
Example, A Super Nintendo game cartridge holds up to 32 megabits divided by 8...the answer is 4 megabytes of space used.
The current CD-ROM video games hold up to 700 megabytes and DVD-ROM video games hold up to 4.7 gigabytes on a single sided disc. You can multiply it with 8 and get the answer in megabits and it may sound impressive!