The PVC clear tubing I buy at the hardware store is the same spool my LHBS has. It's designed for water use.
I buy it at the LHBS to support him, but since he's 25 minutes across town, I only do that if it's convenient.
As to the tubing, don't boil it. You can't achieve sterilization anyway, from a practical standpoint.
Start with hot soapy water, get it good and clean then rinse well with hot water from the tap.
Then sanitize with your favorite no-rinse sanitizer. (One-Step, StarSan, Idophor, etc..) Remember to leave it in contact, inside and outside, for the prescribed time based on the sanitizer. Most are 60 to 120 seconds.