PSP-Flevoland also sells Memory Sticks for storage of your games:

2 Gigabyte costs €15,00 including shipping

Each next 2 Gb stick costs €12,50

4 Gigabyte costs €22,50 including shipping

Each next 4 Gb stick costs €20,00

8 Gigabyte costs €45,00 including shipping

Each next 8 Gb stick costs €42,50

The rebates are also valid for combinations of different sticks. Sadly, the sticks are not always on stock. In that case, shipping takes 10-14 days.