i've doen bt but all for credit cards. 

usually i get chase or discover that has promotion for 0% apr bt. most of them charge 3%. max for $50 or $75 depends on the offer. sometimes you get no bt fee but that's rare.

AND I ALWAYS THROW AWAY THE ONES SAY 0% APR FOR PURCHASES.  but today i happened to look at the capital one letter i got in the mail. it says 0% for purchase.. and i happened to read the "important disclosures" part which has all the interest rate or finance charge information.  it says.. BT apr is same for purchases.. and BT fee: none!!! kaka so i applied