My advice is to do some simple deductive reasoning to find the models that fit your budget. At first glance the sheer variety of options is a bit overwhelming when you first start looking at HD cameras, but when you start to dig into each brand's line up you'll find that it's really not as difficult to choose when you eliminate the features that do not matter to you.
I bought an HD camcorder earlier this year and I determined that the best 3 brands going as far as build quality, picture quality, and user reviews were Sony, Canon, and Panasonic. I then made a spread sheet listing each model within these brand's line ups and the features each one had, then I sorted them by price. If you do this you'll find that the differences from one brand's top f the line model to their lower end model really may not be that significant when it comes to picture quality.
With each step from the top of the line to the lower end on the line you'll find that the features that differ are features like an external mic jack, 64 GB memory vs 32 GB memory, one has an SD card slot and the other doesn't, the size of the LCD screen, one has a viewfinder and the other doesn't, and so on. In my opinion the most important thing you should look for is picture quality. Whether or not you'll be able to add an external mic or increase the memory really depends on your budget.
Another thing to look at is "last year's" models. You can often find smoking deals on last year's models. My budget was $1,000 when I was shopping, but I ended up going with the top of the line Sony model from the previous year. The only difference between it and their new model was that the new one had 64GB of internal memory where the previous model only had 32GB. However, the previous year's model had a slot for an additional 32 GB of memory stick, so to me it wasn't that big of a deal. What was a big deal was that the previous year's model was $300 cheaper! I got the same picture quality with all the bells and whistles (less 32GB internal memory) for $300 less and I can buy a 32GB memory stick for far less than $300, although I've never had the need to do so yet.
Once you have your choices narrowed you should start searching online for reviews. You have to take them with a grain of salt, because sometimes you see reviews written by someone who doesn't fully understand how to use the camera they bought, or some camera snob who is uber picky. You can find some good info though that will help you make your decision. For example, I was dead set on the Panasonic TM700. Earlier this year this was hands down the best camera out there by a long shot as it shoots 60fps in 1080p. I ultimately decided against it because from reading reviews I found that in order to edit the video you'll need a mammoth quad-core computer to handle it. Had I had such a set up computer wise I would have gotten the Panny, but having to buy a new set up put the Panny out of my budget.
Once you are set on the model you want start scouring the web for deals. I found my camera at B&H photo for $200 less that anywhere else. I paid $700 for my Sony CX500V. They may be hard to find now since it's replacement (the CX550V) is now soon to be replaced, but if you can find one they might now be in your price range. I've been using mine since March and LOVE it!