I wanted to try some new pickups, but hate spending $$$ on something I have no idea if I will like. Duncans and Dimarzios are $150 a set and up, with "boutique" winders costing $250 to $400 a set!!!

I had heard about switching in different magnet types, and thought I'd give it a shot on some cheap humbuckers.
I bought some "Dragonfire" pickups (made in Korea, potted, alnico magnets) and "Uncle Willie" pickups (claims he hand winds them, but the parts are Korean, unpotted, ceramic magnets) off of eBay for about $30 to $40 a set. I chose them for price, but also because the DCR was approximate to PAF values (7.5k to 8.5K). Some brands have overwound bridges (16K & up) and I did NOT want those. I also needed gold covers, which both of these offered for low $.
I found a seller on eBay that specializes in PAF style magnets (seller: addiction-fx)....they cost about $2.50 each, and each pickup uses 1x magnet. I ordered some Alnico 5, 4 and 2 to try. They are rough cast, unpolished....just what are recommended for PAF. You can get them "oriented" or "unoriented" for different flavored tone. Do some google searching & you'll find descriptions of the different magnets and the tones they produce. They are also 2.5" long, something I will talk about later.....
I first installed the pickups "stock" to have something to compare to. Both sets were pretty bland, nothing to write home about.
Swapping the magnets is pretty easy, you just need to be careful of the wires, but the magnet just slides right out after disassembly. If the pickup is potted, you may have to work a little to loosen up the magnet from the wax, but it's fairly easy to do. There are youtube videos that are helpful, and there are threads on some of the guitar forums (mylespaul.com, etc) that give some guidance. Take care to observe how the magnet comes out of the pickup, keeping exactly in the same position so you can match up the new magnet's orientation. NORTH is marked on the new magnets, and thankfully it was also marked on the stock units. If you get it wrong, the pickups will be out of phase when combined, & you'll have to take one of them out & flip the magnet around until you get it correct. There was also some guidance for this on some of the guitar forum threads I found.
I've got it down to a fairly quick procedure.....I can loosen the strings, remove the pickup, disassemble and swap the magnet, reassemble and reinstall in about 5 minutes!
About the length of the magnets....all the cheap, stock pickup magnets were ~2.25" long....about 1/8" too short on each end of the pickup. The 2.5" new magnets filled the space in the pickup completely....very nice!
I put an A5 magnet in the neck, and an A2 in the bridge.
After tuning the guitar and doing a preliminary adjustment of the pickup height, the difference in tone was evident from the 1st note....full, round notes with a sweetness the stock magnets didn't have. I adjusted the pickups for balance of volume when switched, and I really couldn't be happier! I can't imagine "boutique" pickups sounding any better!
I am going to try the Alnico 4 mags, and also try the A5 & A2 in other positions to see where I like each type the best
Another note: I have found that I like covered pickups MUCH better than those with bare, open bobbins. The covers give a smoothness and evenness that I like, none of the harshness of uncovered. When I was a kid, it was all the rage to take your pickup covers off, and I just got in the habit of it, or always bought uncovered models. I also noticed that most, if not all, of the pros whose tone I admire use covered pickups......live & learn
Anyway, for about $70 to $80 max, I have 2x very nice sets of "custom" pickups, and I'm having a bunch of "cheap" fun!
Geezer