Maybe interesting:
Re: Rear disk brake wearing fast on 5.0
Re: Disc brake caliper lever bumps into caliper body
Just google for “Hayes MX2/MX3”, guess you’ll find these locally 
Pic from Chainreactioncycles:
http://www.chainreactioncycles.com/Models.aspx?ModelID=8656
http://www.bikestore.cc/bbs47-hayes-mx2mx3-mechanical-scheibenbremsbelaege-p-119656.html
http://www.ebay.com/itm/DISC-BRAKE-PADS-HAYES-MX2-MX3-MX4-SOLE-/320604132340
Compared to the above, the original Strida pads are not that expensive, at least at Vanmoof; you’ll get 2 pairs for 20 €:
http://vanmoof.com/shop/catalog/product_info.php?cPath=112_126&products_id=213