I've been burned by this before, especially by the margin requirements for a short-sale. It doesn't matter how confident you are a stock will crash, because if it keeps going up, eventually you will either need to sell at a big loss or add more money to keep up. And it's very tempting to short even more as it continues to go up, since you'll make even more when it crashes! And then you run out of money and are screwed.
In general, it's not a good idea to start from "this stock is priced illogically" and then apply logic to it.
In a couple weeks, options will be available on the stock and you can buy puts. The upside isn't as good but the downside is capped instead of unlimited.
Wait until the lockout period for the employee options expires, like in 6 months, then short it hard. Do it like 2 months beforehand because everyone else is thinking the same thing.
In general, it's not a good idea to start from "this stock is priced illogically" and then apply logic to it.