The short version: I had one hem on my pants resewn within 24 hours for $3 and it was a great job.
To find this place: Take the stairs down at 111 3 Ave SE between 'Try Again' and 'So Yummy'. Then walk to the back of the mini shopping complex and it's on your left. It's open until 6pm everyday and closed on Mondays.
The longer version: I phoned three different alteration places listed in Chinatown initially. One was closed, another's phone number was out of service, and this one. When I phoned, the phone was answered with 'Hello', but it was the right number for the business so don't be put off if this also happens to you. I checked that they were still in the same location and the time they were open until (6pm) and walked on down. The bars were closed when I got there (5:30pm) but the girl (who appeared to be the daughter who answered the phone) took my pants, my name and my phone number.
I explained what I wanted done and she said that her mother would phone the next day to let me know how long it would take and the price. I was initially quoted 4 - 6 days and $8 - $13 for the hem. Turns out since I only wanted one leg resewn rather than hemmed it was $3 and 24 hours. Plus I tied this in with a takeaway dinner from Han's Kitchen nearby, and now have my work pants ready for the cooler days.