Elwin,
I'd have to second the "start in the middle and work your way out" approach. This will give you the maximum versatility up front, and allow you to evaluate your future needs.
I started out with a Steel Heart, worked my way down, and now am ready to fill the top end niche with a Basic 9 right now, and will start the quest for a steal on a Straight Handled Battle Mistress.
The Natural Outlaw is a good central "balance" of big enough to handle chopping requirements, while giving the dexterity of a smaller blade.
The Satin Jack gives you a straight-handled blade that is fantastic for field use.
The frequent monitoring of BladeForums Exchange threads, as well as Ebay, can lead to some great deals on the INFI of your liking.
Have you had a chance/opportunity to do a hands-on comparison? If you can get to a show where Busse is represented. Be careful. Touching INFI will cause a case of serious INFI-purchasing obsession, of which the only relief is to buy more INFI...
I don't know your intended use, but am confident that you can find well founded guidance here in helping you to select your first.
Hope this helps some.
Mike