If $1500 is way crazy, but you still want to go nuts, then a DiCAPac can work. I have one, and it's mostly fine (even underwater)..
Assuming that a bit more risk is acceptable, and that you're thinking 'light rain' instead of 'hurricane and a bit of river rafting', then maybe a simple rain-jacket would be fine.
I use these that Cory posted. They work pretty well, moderately durable all things considered. I always have one in my bag. They also work wonderfully for snow. Of note, the non-flash one is big enough for a 28-70 with a flash, but not a long lens and a flash. If you want a beefier nicer version, get one of the Thinktank Hydrophobias. Those things are damn near industry standard for sports (and many nature photogs), but be aware that you also need the eyepiece for the product and that they don't tend to work as well on smaller lenses. This is last bit is somewhat true of the optech bags too, but not as much as it's a thinner/more pliable material, ergo less durable.
ETA: The optech ones work pretty well for blowing sand if you just close up the end, as well. I never purchased the Hydrophobia because I simply don't get that much rain in Colorado (normally...).
I've used the rain sleeve that's been posted before. I've also just cut a hole in a plastic bag from target and wrapped it around when desperate. If I'm out for a short time, I just shoot one handed and use an umbrella -- it's easier than the sleeves and the bags, because I can get to my controls. But my camera is so heavy one handed, it doesn't work for long.
I never purchased the Hydrophobia because I simply don't get that much rain in Colorado (normally...).
Speaking of, how are you doing up there? We're floating down here...
I live on the western slope now, which has been all but untouched by all this (we had around a week of rain and some swollen rivers, but not even fields were flooding). All my family lives down on the front range, and largely in Fort Collins, but luckily the actual in city damages haven't been too bad there, it was more that there was strong potential for bad conditions since the river runs through the city. They closed every bridge as a precaution. I haven't spoken with Hahn, but he's more likely to have been effected this time around than I, since Estes saw actual flooding throughout the city and highway 34, as well as highway 36 and highway 7, have been washed away in places, so the only access by road is over trailridge road in RMNP, which will likely be closing soon due to snow anyway.
I use Think Tank, Hydrophobia gear for all of my stuff. In all seriousness, if you are going to shoot in the rain with expensive gear, why rely on a freezer bag or other non sense. Buy something that is made and designed for the intended use. I've shot games in the leftovers from a Hurricane with a D4 and 400MM F2.8 and a D3s and 70-200 F2.8 without hesitation. And I have never had a failure from the gear. Yes it's expensive, but it's a very small sum compared to replacing even one piece of my equipment.
