If you are looking for strong magnets, find some Permanet magnets. The best are SmCo5 (I don't know how to write it right on my keyboard), Sm2Co17 (again the same), sintered NdFeB, bonded NdFeB, and AlNiCo. They are all good in different ways depending on what you want. All of them should work in the size and weight though in most cases.
I have been working on using them to hold stowage on my models, so I can change them when ever I want without totally reworking the model.
I haven't restocked in a while, but you should be able to get them on-line for about $0.15 to $0.50 for the size you want. I got my help from a member on a board that is a Science Teacher, so if you look for more information track one down. They are a big help.