The cycles are impossible to predict now. The nVidia 780's were 700$ when they first came out, and that wasn't very long ago, late spring early summer. They are now as cheap as 450$ for the exact same card, and the new 780 TI is in the mid 600's and is even faster than the 780. This exact time last year I bought 2 of the fastest cards I could get, and the fastest single card (Titan) for a brief time as well. The 680's were nearly 1200$ total for both, now they are almost impossible to find only a year after debuting as the fastest SLI solution out there, and they are well under 400$.
This isn't even going into the AMD line of cards. The back and forth of the last few months has been great for prices and those of us on the customer end of things. I don't think anyone predicted that when the AMD new cards came out a couple months back that it would force nVidia to slash the price of its flagship cards by over one third.
All you can do now is just buy the best you can afford and be happy with it. If you're lucky you may catch the wave at the perfect time, and be buying when a huge price drop occurs, like with the 780's recently for example. But that's what it is, luck, as I didn't see a single site the day before the price slashes happened predicting it. Tom's HW guide is pretty much the best game in town for finding the cost/performance ratio for any price range. Trying to keep up and have the best card all the time is a full time job almost now. I sold the 680's from one machine and went to a single 780. Now the 780 TI is out, but I'm not falling for it again, and I'll just keep my 680sli and 780 machines the way they are for the next year or so.
