Gas isn't expensive today. What's expensive today are almost all commodities. http://www.indexmundi.com/commodities/
This is a systemic problem. Any valid explanation of price increases in a commodity, e.g., oil (gas), has to explain why prices are rising almost across the board.
Global commodity price increases are being driven by two main factors. The first is rapidly rising standards of living in the developing world as many nations, especially China and East Asian countries, have freed up their markets. This has caused a dramatic rise in living standards and a huge decrease in the number of people living in poverty. These people are now buying the things that we in developed take for granted, and that is driving the prices of copper for cars and new homes, steel for buildings, oil for transport, corn for livestock feed, etc.
The other systemic factor is massive currency inflation in almost all OECD coountries. When inflation happens in more normal circumstances, an inflating country's money falls in price relative to those of other countries, and it's easy to see which countries are destroying their currency and which aren't. People sell the increasingly worthless currency and buy the strong ones. What we have today is almost all OECD countries inflating their currencies at once in a (failed) effort to boost their economies. This means that anyone who wants to protect their wealth needs to invest in something that will rise at least as fast as inflation. That means commodities.
BTW: If speculators can somehow control prices in a way largely independent of constraints, then why aren't they always doing it? It's not like human beings just started getting greedy last year. And why have, for instance, prices of natural gas fallen thru the floor (hint: greatly increased supply due to drilling breakthroughs)? Where are the all-powerful speculators on that?