I actually found HD disks to be of much shittier quality than its DD counterparts. I personally use the "tape the hole" trick, it works well (and with certain brands of disks, you can be sure the data wont get corrupted), but recently I got a hold of about 200 DD disks that I can use as blanks... Buy them at shops? No way, they stopepd selling them for about 4 years now...
You could look at eBay, but there is a shortage. BNest bet is that you should use HD disks with thehole covered.