One of the first lessons of high end collecting I learned was not to pay up front if you can avoid it. I got burned a couple of times, even by a seemingly reputable company that went belly up and then shrugged their shoulders when customers came asking for refunds. This happened with Big Chief Studios recently.
Mondo seems like a reasonably successful company, but. . .who really knows, and when you may be waiting a year or more, you won't have any protection from your credit card company if they end up not delivering.
I don't like this situation. Would like to have this guy, and I don't think I would get the regular without the monsters, but this is giving me pause. Plus, as others have mentioned, it frankly doesn't look like the price matches the product from what I'm seeing. Even SSC would do something of a higher quality than this with their prototype. If it were < $200 it would seem more reasonable, but given that they charge over $50 for posters (many $80!) I guess this is no surprise. You pay Hot Toys prices for a Mezco like product.