So why people pays 10 times more for AsicMiner when they will have same amount of dividends from 200TH mine.
Because hashrate of AsicMiner is increasing and every share gets more hashing power over time.
With 100TH (now 200TH) bitcoin mine you get 400MH/s for every share and that is it.
For some period of time, investing same amount of BTC into AM and 200TH will give ~3 times more from dividens from later. Do your own math, my maybe wrong though.
Let me explain really simple.
You buy 1 share of 100TH mine for 0.2BTC.
In 1 month your 1 share have produced 0.05BTC.
But price of share has dropped to 0.1BTC.
Another months passes your earned additional 0.03 for total 0.08BTC, but
share price has dropped to 0.05BTC and is now worth 0.05BTC.
Total earned 0.08BTC with share price at 0.05.
Or 0.2BTC invested 0.13 returned.