I think I read somewhere that only the Inuits/Eskimos, etc. (those who have a legal right and limit to harvest a seal) can use/or sell seal skin and that of course limits the supply greatly. I also happen to love sealskin for shelf pads and arrow passes. Bear hair rugs, and also the softer part of the velcro type fasteners make pretty good replacements.
That having been said, let me mention this though. The indigenous Native Alaskans used to (and may still) make belts out of many small discs of sealskin and brightly colored cords and felt disc backings, for sale. One old time member (don't recall who) on one of the trad forums (perhaps here) mentioned a few years back that he was lucky enough to find one in a second-hand store. Not 3 months later (after being forewarned and forearmed) I also found one, in a miscellaneous items box, at a local flea market. I scarfed up the "belt" for a measly $1.00, and have a lifetime supply of sealskin. Not bragging about my good fortune to rub it in - just trying to forewarn others to be on the lookout for this possible bonanza:

As you can make out, the second (or inner) layer of discs is lighter in hair/fur color, and there is about twice as many as in the top (outter) layer of discs. You can also see the discs of sealskin are a little bigger than a quarter and plenty big enough for a self rug or arrow pass (in most instances). I just unlace and remove one or two as needed - nothing is sewn or glued in these belts.
Be alert (I almost missed my opportunity) - besides, the world needs more Lerts - LOL
If this helps even one person (as the previous members post did for me) it will be worth it.