Compare all the stats you want: the majority of consumer decisions are made first and foremost on price, and module prices have decreased for the last several years. Global fluctuations in demand have and will likely continue to occur—entire nations have implemented, adjusted, and/or repealed various incentives for grid-connected PV systems. Furthermore, it takes time for manufacturers to scale up to meet demand. Combine these two factors, and the result is a market where supply can, and often does, exceed demand.
Solarbuzz is a company that tracks PV industry price trends (see www.solarbuzz.com). Their retail module price index shows modules at an all-time low of $2.65 per W as of September 2011, around half of what modules cost at the start of 2002. These are retail prices, with distribution and installer markups included, and do not take bulk pricing into consideration. Many modules are available for less than $2 per W, with some below $1.50 per W.
Many utilities and states are reducing rebates for PV systems. Fortunately, this corresponds with all-time-low module prices, meaning system costs are decreasing ($ per installed watt) as well. As in any market, prices will continue to fluctuate based on supply, demand, and government support of the industry.
When thinking about purchasing cheap modules, realize that you might get what you pay for. Quality matters, and often it becomes a factor over time. Consider how long your module manufacturer has been around. Reputation must be earned, and word of mouth has impact.
Module prices aren’t part of this list because, like any commodity, price isn’t fixed, but rather depends on who you know, how many you buy, and what overall manufacturing price trends are.