Although there are manikins out there that are much higher quality, the "alien" manikins will do just fine. I would not spend the money on the expensive ones until you have the profits rolling and business is good. Just some food for thought; depending on who you instruct through (ARC, AHA, etc) they actually have regulations on which manikins that you can use. ARC actually has a list published that specifiies the brand and model of manikin that is approved for their courses. The "alien" model is not one of them. I doubt anybody would call you on it, but just be aware of the fact.
If you are just starting out in the business, I highly suggest you read "Safety Training for Profits". It has a ton of invaluable information on how to make money teaching CPR and First Aid. Alot of businesses do this but if you want to be highly profitable, its a must read. You can find it at www.cprcash.com . Its a cheesy website but the book is great. Best of luck to you.