I have contacted a couple companies willing to do custom orders of coated magnets but they all require minimum purchases that are only feasible in a group purchase. I have found a couple gold plated n52 3mm by 1mm (Same size as m31) and am planning on testing a large batch of around 500 in a heavy salt water solution and a bleach solution and check for impurities in the gold. I'll coat it in a second layer of preferably titanium nitride. One company called azind creates custom N52's of different sizes and coats but only does them wholesale.
If people are willing to do a group buy it's possible I can set up a fairly large and inexpensive way of manufacturing high quality m31 'clones.' Azind is asking for $166 for 100 magnets coated with tin (I am attempting to get a gold and tin coating, and this price is based off of information I got from another user. I am contacting azind to get an exact quote) and the gold plated n52's are only a couple dollars on ebay (obviously these will be tested, don't immediately assume I'm not proceeding carefully. I may also use azind to get the gold coating)
I am also considering using 5 smaller approximately 1.5mm by 1.5mm and placing two of them on each side of the finger and one in the center. This would allow for a large amount of nerves to be stimulated and can give a slightly more 'tactile' feeling to fields. The magnets are to big to fit in the capillaries and would be coated using the method suggested above making them just as safe as the popular m31. More about how this can be successfully done without friction/shifting is talked about later on.
In a later comment I explain a unique method of assuring everybody gets implantable magnets. This solves a large portion of most peoples reluctance to participate in group purchases because they believe it is a gamble.