We have all seen the pre-packaged memory games in the retailers. They are fun but you can make one for next to nothing that is focused on your child's interests.
We have a huge beach/fish theme in our house so we made one with that theme.
I was in Goodwill, which is a great place to find supplies for crafts and activities for next to nothing. While cruising the aisles, I saw a HUGE bag of shells for $1.00. There were near 200 shells in this bag. I went ahead and purchased it having no idea what I would use them for. After a couple of weeks of staring at them and picking them up after my son played with them I decided to make them into a memory game. I dug through our sticker stash and found some beach themed stickers. I needed two of each stickers so I just dug around until I found matching ones. I did not have enough beach themed stickers to make a whole game so I did use some other animal stickers but my son does not seem to mind. Most of these stickers came from Target's dollar spot or from Michael's dollar area.
I found shells that were close in size and then I cleaned and dried them well. Once they were dry, I just stuck the stickers inside them. You can not have stickers that are too big so keep that in mind when looking for stickers.
When it is time to play, just lay the shells in a grid, sticker side down and then you follow the original memory game rules. When we first started, I set the matching ones side by side to let him learn the concept.
As for storage of my homemade games and manipulatives, I use empty food containers. The memory game is stored in an empty oatmeal container. I used card stock to cover the old label and secured it with double stick tape to the outside of the container. I then made a label for the container.