The magnets are fairly easily positioned by using bolts. Drill two or three wholes in the magnets and in the base accordingly. Then you attach the magnets to the bolts, using a nut. Now you can attach the magnets to the base using two other nuts. By positioning the nuts on the bolts, you can position the magnets. This is a pretty easy and flexible system.
Now where to get these powerful permanent magnets? Simple... You trash a computer hard disk. The older models of hard disks (before 1998) have these powerful magnets inside to allow them to write on the magnetized disks. The old disks are worth almost nothing, so you should be able to find some that no-one needs anymore. You could check the informatics department of you university, or go to a computer repair shop, or maybe you even have some at home.
Be careful with your news toys though. These magnets are very fragile, and too many shocks cause them to fall apart into 1000 little pieces. Watch your fingers too, they are more powerful then they look.
