I would like to at least have the ability to retire by the time I am 40...What is a good figure to aim at? *$1M, $5M?
I resemble that remark, but I have no idea how to answer your question because I don't know what your expenses are now and what they may be when you hit 40.
A good estimate to use would be to take your realistic budget and multiply it by 25 to get to your estimated magical net worth. For example, if I estimate my budget at 40 to be $50K a year, then my net worth should be at least $1.25mil. In my case, I should be under that at about $950K to $1mil, but I plan on working just enough to meet the gap. Plus by earning anywhere from 15K to 20K a year, I will be able to throw most of those earnings back into the pot in Roth IRAs.