looking for information on magnets to buy

i'm looking to buy some magnets, but i'd like to get a sense of what to look for. I've looked around and it seems that the strongest rating for neodymium magnets is N50 and the strongest for ceramic is C8. the only thing is that i have no idea what these ratings mean.

ideally, i'd like a powerful magnet about the size of a brick or a little smaller so that i can attach them to a long beam of metal that i can use to drag along the bottom of a creek or beach shore and pick up metal bits along the way. because of this, i'd also like the magnet to be tough, and not brittle.

i'm wondering if anyone could impart on me some wisdom on the kind of magnets i should be looking for and how much i would expect to pay for a nice big one. wondering also if there are places you can scavenge magnets like these, like at junk yards and what machines contain these kinda of magnets. thanks for the help!

>>3

yeah, i've pinched my fingers with the hard drive magnets before and it was no picnic. i'm fully aware of the care i must take when handling the bigger magnets.

i saw there are some big magnets in a tool that lets you pick up and love metal sheets, and it has a lever on the side to pry the sheet off with relative ease. wondering if i could get one of those, but whenever i look they're like $200+.