Wow, an American thats thinking logically, what a shock. You have laid out one of many reasons why housing IS currently NOT worth close to what it should be.
If you want a McMansion, you need to change a few bad habits that you have. First, stop saving your money. It is common knowledge that this will get you nowhere. All the successful, McMansion and Hummer owners use loans. They’re easy to get, and you don’t even need to prove your income or credit worthiness. The bad part is that you don’t even pay of your house, but you shouldn’t worry about this petty fact. You will own a home. Second, don’t worry about that down payment either, you can finance it all baby!! And finally, you need to get all emotional about buying a house, and stop doing math, that won’t help either. Make sure you find a nice high tax area too! Good luck.