Scubaalp,
I think people in this thread are overly hard on the way you've chosen to go pro. In my opinion, doing a divemaster internship somewhere cheap also has some benefits. You'll meet tons of different divers and if you're smart and humble you'll learn some from the good ones. Doing as many dives as you're likely to during your internship (100 a month isn't impossible) you'll also improve your skills tremendously.
Of course, as everyone points out, it's a very different deal diving in cold water with bad visibiity - and learning how to dive, and becoming a pro in a tropical paradise will not adequately prepare you to teach in conditions similar to those at home. But is that what you want anyway? If not, why bother learning in conditions dissimilar to where you want to live and dive? Even if you plan on working at home - doing an internship in the tropics isn't nescessarily a bad idea - you'll get hundred of dives (make sure your internship has unlimited diving) and the weight of that experience makes you calm and collected in the water - something which will help you adjust adjust to bulky suits, cold water and challenging conditions at a later date. Just allow yourself some time to get into cold water - don't think you can do the work straight away. I tried, and I still cringe when I think about it. =)
Tropical diving at recreational depths is very, very safe - and if you apply yourself, you can become good at doing divemaster work in such conditions in a fairly short time. You can be an excellent divemaster by Utila or Koh Tao standards in a few months - It's simply not true that it takes years to get to that point. If you can at all, I'd find a grizzled veteran who's been around, and get him/her as your mentor. Preferably someone who's also a tech diver. Puppy-farm destinations have a wealth of very inexperienced instructors, who regurgitate erroneous information they themselves picked up from other bad instructors. I did my divemaster course on Koh Tao ten years ago, and was (quietly) puzzled by the many cases of misunderstood dive theory I overheard (and I'd only read and understood my Encyclopedia of Recreational Diving.)
Your most difficult challenge ahead is finding the right mentor - these thread are full of advice like "Go to whatever diveshop - they're awesome" and that's just completely useless information. (no offence intended to any posters) Often students (also new professionals) recommend teachers without realising they had been taught outside of standards or have been filled wth erroneous information. What you want to do is go somewhere (or an internet forum), and find one of the old time instructors (private message them if on a forum). Befriend him and ask who he respect and thinks is a very knowledable instructor, and who'd be a good mentor for you. Get a second and third opinion also - then find out whereever that guy works, and ask to do an internship with that guy. Pay extra if you must, but get that guy. There's very good people on Koh Tao and Utila - they're just surrounded by people who didn't learn from them.
All the best,
Soren