I don't know what we are looking for, but I was doing some work with some high power neodymium magnets for a science fair a long time ago, and this site worked great:
It does seem to be USA focused, so shipping may not scale perfectly internationally. Also most measurements are USA Customary System Inches, and not Metric so that may be rough as well.
They do have pretty much every size, shape, and coating you could think of though. They also have different grades, but I am no expert on that so i'll let someone else decide if that is valuable.
This may be a redundant source, but I just wanted to share what I used in the past.