I was actually looking at magnets at the $ store and found a package of magnets- see picture below:
Then I saw these:
This is also tiny so if you have only a small surface area to sew on, then this little magnetic pin cup would work for you!
One package of magnets and one of baking cups = 4 pin holders .
Sew... give one to a sewing friend!
There are some other alternative solutions/purchase options if you want a pretty coloured pin holder and if you are not a "DIY'er".
Some of the below come with additional features as well and they are: