We go through labels like crazy. At first I bought from the more internationally popular brands like Stuck on You and BrightStar. I will say, I love Stuck on You's shoe labels and both Stuck on You and Bright Star's pencil labels. Stuck on You also does fancy stuff like slap bands and products.
But, and there is always a but, they are pricey for the amount we need. The kids get A LOT of books, and they all need to be labelled.
Also, my kids need bilingual labels - with their Chinese and English names - and some of the international sites cannot do this, others can but with time consuming work arounds.
So I researched some other options more specific to Hong Kong.
Then I found that UR Photo in Hong Kong does labels, including washable ones - got a whole bunch and they are great. We use these on books, rulers, water bottles, their chopsticks box, and anything that needs a more durable sticker.
HKIOU wins the award for cheapest, and most ancient website - you have to confirm your order by FAX... needless to say, that didn't happen! We go to their 'stall behind Sogo' in Causeway Bay, to get small cheap labels for pencils, scissors, glue, lip balm and other small items. Their iron on labels have mixed reviews, so judge for yourself. See the map link below for the exact location or use this in Google Maps 銅鑼灣駱克道517號.
My recommendation is to get a 'pack' that comes with shoe stickers, pencil stickers, large, medium, small labels to start and maybe some iron on labels. Then you can see what you use most and supplement with specific orders of those. We run out of pencil stickers constantly, so having a huge cheap supply of those is great!
Meanwhile, on a local HK moms forum lots of people posted their ideas so I checked them all out and made this list below for your convenience. All of these ship internationally for a reasonable price or for free.
UR Photo - Hong Kong - waterproof, well made and can even put photos on some labels - good value for the quality
HK IOU - Hong Kong - cheap and cheerful, great for pencil stickers
Fotomax - Hong Kong - can shop online or at one of their many shops
ID Me Labels - USA - good 'packages' which include laundry safe stickers for clothing tags
Stuck on You - Global - great quality, good 'packages' and special items too
Bright Star - Australia - great quality, good 'packages' and customer service
TinyMe - Australia - name labels, bags, water bottles, wall stickers, more
Cash's - UK - name labels, iron on labels, travel and woven labels too
Mine4Sure - France - ID bracelets, allergy labels, and the usual name labels too
Name Bubbles - USA - cute designs and allergy stickers too
Name Labels - Denmark - have large sizes and very cool temporary tattoos
Stamptastic - UK - uses a stamp for paper and clothing not plastic
StickerKid - Switzerland - see review from TrilingualMama here
Woven Labels UK - UK - offer ribbons too
GB Name Labels - UK - luggage straps, cool accessories, special labels for scouts