Under $1000 your choices will be pretty limited. When I was shopping for a rear tine tiller I found most were either $500-$800 or approaching $2000+. The new under $1000 choices will be limited to smaller Troy Bilts (MTD), assorted AYP products (Craftsman, Husqvarna, Poulan) or MTD machines (Cub Cadet, White, Huskee, etc.). Aside from Troy Bilts being built a bit better than the others, but not nearly as well as they were built pre-MTD, I don't feel that there is much quality difference between the machines in the sub-$1000 price range. Mostly they offer different features, engines, and some have better parts & service support than others.
I bought a new Husqvarna 700DRT a couple of years ago to expand my garden. So far it has been a good machine. It ate 1 belt right after I bought it, but that was because a pulley was loose. I fixed that and it has been flawless since. I purchased the Husqvarna for a few reasons: 1) I liked the dual rotating tines. I can till in forward rotating mode to cultivate or in counter-rotating mode for deep tilling/sod busting. 2) It has a B&S with cast iron cylinder liners, unlike the cheaper AYP built tillers. 3) I have a great local power equipment dealer & his price on the Husqvarna was only slightly more than Sears price on a comparable Craftsman that didn't have cast iron cylinder liners.
Regardless of the brand you buy, I would look for a tiller with a quality engine, preferably commercial grade, but that's tough to find in this price. At least get a B&S with cast iron liners or a Honda GC engine. Some new models from MTD & AYP (I know for a fact Craftsman) have Chinese engines on them. Also, I would suggest a model with dual-rotating tines so that you have the versatility of counterrotating and forward rotating tines. Counterrotating tines are only OK for cultivating but great for deep tilling, and forward rotating tines are great for cultivating but only so-so for sod busting unless you have enough machine to hold itself back as the tines try to push it forward. Finally, you can't really buy a tiller with tires too large--you get more clearance under its belly and better traction so that you don't have to wrestle the tiller as much to keep it moving in deep, soft soil.