I have an Ex-mark Lazer Z. Yes it's expensive but they have pretty good payment plans. I've had mine for two years and I can't say enough good things about it. I actually look forward to mowing the grass!
Stay far away from the lawn tractors. I have 1 1/4 acres to mow and I get it done in 45 minutes or less. When I see my neighbor on his lawn tractor mowing his yard I'll give him a 45 minute head start and I'll be done before he has half of his yard done.
When I bought my Lazer Z the guy asked me how many properties I had to mow. I told him just mine. He asked how many acres I had and when I told him an acre and a quarter he said my new mower wouldn't even break a sweat on that. He said that my mower was designed to work every day all day. He was right. It rocks!
Mark is right, with higher end mowers they will deliver a mower to your property so you can test drive one on your own lawn.
http://www.exmark.com/ride.htm