I bought my brand new Canon 70-300mm L in December 2010 from a bricks and mortar store (with a fantastic returns policy) here in Australia, for AUD$1600. It had been $1700 the previous week, and I jumped on the $100 special. Plus I received a quality 67mm CPL filter for about $50 off the RRP, so in effect I was getting my lens for less than $1600 – and that was just about a month after it was really hitting the shelves (a month or two after it's international release).
Sure, I could have waited more than a year – and probably obtained the lens for a bit less than that, but I’m glad I didn’t. I have taken so many photos with this lens since Dec 2010, I’m very happy. Plus, I have seen the lens (in the same store that I bought it in) for $1800 for a lot of time – even during 2013. Probably a result of demand and supply and international currency rates, etc. The IQ of the 70-300mm L is definitely a cut above any other 70-300mm / 55-250mm lens (and I’ve used all of them).
Read real user reviews, and the vast majority of people who purchased this lens are very impressed with the IQ & handling this lens. It retains superb IQ throughout the focal range, wide open – which the non0L 70-300mm can’t do, neither can the Tamron 70-300mm USD (which was the lens I was also considering). The 55-250mm (including the latest STM version) are good for the money, but they don’t compare at the tele-end (eg not as sharp, less contrast, inferior bokeh, higher CA). You do get what you pay for. Sure there are some poor ‘dud’ samples / copies out there (eg the one that SLRgear reviewed) – but nearly all of them are good (I’m very glad mine is a superb sample).
All the best.
Paul