I also have the same advice most are already giving here; spend your money on goo, full frame glass. I used the A99 for about 10 days, and I have the A77, so I can tell you that while, yes, the A99 is better, the A77 still holds its own. The real differences (and I mean BIG differences, because the A99 does have many other edges, but they are not astronomical as they are in these) are:
1. Low ISO resolution. Here the A77 is literally blown out of the water. I am talking about usable pictures at ISO16,000 and even 25,000... The A77 is spotty at anything above 3,200 (and I rarely exceed 1,600 to avoid noise).
2. If you take portraits (or pics with lots of detail) or want larger viewing angles. There is just no way an PAS-C sensor, even one as good as the A77's, will compete with a full frame one.
3. If you shoot video a lot. Yes, the A77 is incredebly good, but the A99 is MUCH better, and has many features that the A77 just cant compete. Think of movie quality video with INCREDEBLY good surround sound, and this is what you can do with the A99
Things to keep in mind, though:
1. If you shoot burst, the A77 is faster than the A99
2. If you own a flash, it will not work on the A99 (hot shoe is different)
3. If you have any DT lenses, you can use them in the A99, but they will cause a vignete.
I was at the same cross roads, and, even working for Sony (which I do), I decided to stay with the A77, as I have the Zeiss 18-80mm lens (the 70-300 G lens is full frame, though), and I have 2 flashes that would also need replacing. So in my case, the cost of replacing is too high, and the A77 is at a level that gives me results that I like. Sure, I wish I had the ISO capabilities of the A99 (i really dont use Video all that much, as I have a dedicated camcorder, and the detail level in the A77 is not bad at all), but I rather spend in good glass at this time than a new body, but to each his own. but trust me on this, I REALLY had to talk myself out of the A99, as it is one SWEET camera! And it's even MORE difficult to say no to it when you had it for 10 days to goof around with!