Weather cycles in many parts of the country are affecting the number of available straw bales. For example, drought in the Southeast has had a significant impact on the grain markets. As a result, more farmers are baling hay than producing grain crops. This means there is simply less straw available to builders and other end users and the price of those bales is higher than last year. A more global impact on straw bale availability and price is seen in the agricultural commodities markets. Prices for grain is rising in most countries and as a result, governments are actually buying less for international aid and long term stock pile reserves. This means that although the value of the grain is higher, finding a buyer may be more difficult. Partnered with this trend is the growing demand for corn based fuels like ethanol.
When these two trends are put together, you can see why many farmers are moving towards planting more corn and less grain crops. Less grain planted means less straw bales available and higher prices for that straw. Although this is not a major concern at this time, it is something to pay attention to when planning for a straw bale house. Be sure you consider rising prices when you create your budget.
Another option is something that was asked of me this last week: what about using baled cardboard? Absolutely! As long as the bales are tight and dry, any material can be used. There may be concern from the building department, but that is nothing that cannot be worked out. I have seen people build beautiful homes with baled cereal boxes. The bales, if tight and dry, will work perfectly to create beautiful and well insulated walls. I do not, however, have any data about the R-value of such walls. Get creative, be resourceful, and have fun!