How much do you have in your checking account? (You can RUN that much on your rear PTO...)
Seriously, you can reasonably expect to handle attachments in the 48" (I love running my neighbor's new 2520 -- yes!) size range.
Depending upon mowing conditions, etc. you could even stretch out another foot on a finish or brush hog and make do. (You won't be knocking down 3 ft. grass with it or chopping up 3 inch brush, though.)
AKfish