I run a 48" Busy Bee or something like that behind the tractor. It's an el-cheapo (about $450) and it works well. I only cut our 8 acre pasture at the house with it about 2/3 times a year so there was no sense investing in a more expensive model. I've also used a walk behind brush cutter for years at the farm to cut around the lake and get to places where the farm tractors can't go. Forget all their advertising rubbish, using one of those is hard work and extremely tiring, especially during the summer heat. You have to walk through all the trash that it cuts and you are continually tripping over the 2" high stumps that it leaves. I have one of the older units with no reverse gear so there is a lot of rugging and tugging associated with it's use. I'll say it again, it's hard work.
One option that may be worth exploring, since you only have to do it a couple of times and hopefully isn't too large, is to hire somebody to come in and cut it for you. Around here the guy that I've used charges $25/hour though some of the members on this board have said that it can go as high as $40/hour. I had him cut our pasture the first couple of times, when it was really bad, and now I just maintain it.
