Prices have been climbing every year, there are usually two price increases each year applied to selected lenses. The longer you wait, the higher the price. There are usually sales around Christmas, and with the poor economy, Canon has extended their lens rebate thru the end of July.
Last year, Canon had some very good deals due to their poor 4th quarter sales performance and high inventory. They wanted to improve the sales figures for FY 2011. When that happens, you can catch a good deal.
To note though, those sales are only in the US.
I picked up my 35L last year during the sale for $1100 USD in the U.S., saving myself close to $700 off the Japan retail price.
I learned last night that not only is the 35L a fantastic landscape prime, but a great fireworks lens as well
Sorry, off topic. I'd say you can never go wrong buying new lenses, anytime, especially L lenses. They don't lose much value. For instance, buying a 24-70L I new for 1699, using it a year, and selling it used for 1299, it only cost me $400 to use it for a year, or even two or three years. Not bad.