Right now we have a 10x12 and we only have about $350 invested in it. Don't get in a rush, you will spend more money than you need to. Look on freecycle.org, craigslist, do like we did call a local mirror company and as for their scrap wood. We got 3 full truck loads of lumber for free. Go to your local lumber yard and ask for the old wood and you can get a huge discount. After saving so much you can probably afford to hire someone to build it for you.