Much like mobile phones, ThinkPads were status symbols in the 1990s and early 2000s. The money to purchase a ThinkPad during these periods could buy a used car, fine jewelry, a year of college, and so forth. With laptops now often costing less than a smart phone or a school textbook, it's easy to forget how unobtainable laptops (not just Thinkpads) were to the majority of the population until fairly recently.( In fact, I didn't purchase my first laptop until 2003; it was a Dell Inspiron 8200 purchased for $1600. Though it was an inexpensive consumer model, in today's market, this would be in the high range).
Now, this is a bit of a rough science, since I had to use the price of the system being reviewed. Admittedly, they are significantly more expensive than base models, but I don't think most of us would be selecting the lowest specs, anyway. When controlling for inflation, it seems the greatest change in price was between the T60 and T400 (a 43% decrease); this price drop allowed me to buy my black beauty in 2008 :). To further emphasize how much our world has changed, a T440 costs about 30% of what a ThinkPad T40 did, a 70% reduction in a decade.
So...in 1998, for the price of an IBM 600 (the predecessor to the T series), what could you have gotten? Well, the money could have gone for half the price of a new Ford Taurus (interesting design, isn't it? I guess you love it or hate it. I'm in the former).