I reccomend www.reptilebasics.com for heat tape and supplies.
(i myself and friends have had really bad experience dealing with mgreptiles.com and i know someone will try to point you in that direction... just a precaution)
I would recommend www.beanfarm.com too. I live in Hong Kong and have bought from them many times. Their customer service is very good, answered all my emails very quickly and I usually receive what I ordered within 3-4 days.
We buy our heat tap from www.calorique.com. You are going to find heat tap just as cheap as them but certainly not any cheaper than them. However, you have to buy it in either 100 foot rolls or 500 foot rolls. I had a little problem too with MG as well. They were very late in shipping but they made up for it by giving me an extra 10 feet for free. They were very sincere with their apologies to me too. I'd buy from them again if I had too.