Hi,
Couple of thoughts on this.
1) It depends on what you're looking to get out of the experience -- to me, the biggest benefit of going to a top school is the lifelong reputation and alumni network you become associated with. Every time someone sees your name and resume, they associate you with that school's brand. For the top schools, this is a very good thing - when you factor in the higher starting salaries that come with these schools after graduation, you can quickly get back your money and have the value of the network and connections of an elite school for life. So, if you can get into a top school (Harvard, Stanford, etc.), I would say it's definitely worth it.
2) The story is a bit more muddled for a 10-20th ranked school. Although these schools are also very good, they don't quite have the brand reputation of the top schools and the tuition is almost the same, so the return on your investment is a bit more muddled.
Bottom line is: If your goal is simply to get a decent job after graduation, then any number of schools could be appropriate, but if you are looking at this as a longer term investment, then you should seriously consider trying for one of the top schools (if you feel your profile fits). Also, you might find these resources helpful, they rank b- schools based on the value for the money.
Hope that helps...