Someone going by Kouchan66 has developed an adapter to use full-sized Memory Stick Pro Duo cards in a PSP Go instead of M2 cards. That adapter can be used in conjunction with a Micro SD-to-MS Pro Duo adapter to use Micro SD cards on the PSP Go, with a theoretical maximum capacity of 512 GB. This is useful because M2 cards are limited to 16 GB in capacity, discontinued, and absurdly expensive.
Since Memory Stick Pro Duo cards are physically larger than M2 cards, the adapter uses a ribbon cable to fold into the PSP Go; you'll have to open up your PSP Go to properly install it. Not a major hassle, and the process is fully reversible (EDIT - Maybe not quite? From the store page, via Google Translate: "Although it is slight, processing to the PSPgo rear cover is required."), but you'll need a screwdriver.
You'll also need to trim off the plastic dividers between the contacts on the MS Pro Duo adapter you'll be using. That part isn't reversible.
Kouchan66 is charging 2300 yen per adapter, and shipping to the US is 800 yen (about 28.50 USD total). Here's a rough guide for going through the checkout process:
Limit me to 16 GB of storage if old.
Since Memory Stick Pro Duo cards are physically larger than M2 cards, the adapter uses a ribbon cable to fold into the PSP Go; you'll have to open up your PSP Go to properly install it. Not a major hassle, and the process is fully reversible (EDIT - Maybe not quite? From the store page, via Google Translate: "Although it is slight, processing to the PSPgo rear cover is required."), but you'll need a screwdriver.
You'll also need to trim off the plastic dividers between the contacts on the MS Pro Duo adapter you'll be using. That part isn't reversible.
Kouchan66 is charging 2300 yen per adapter, and shipping to the US is 800 yen (about 28.50 USD total). Here's a rough guide for going through the checkout process:
Limit me to 16 GB of storage if old.