Today, we're running into a similar situation where you probably should always go higher with a 5 if the ARP beings with a 1. The Nissan Versa, one of the cheapest cars currently on the market, as seen on today's playing of Let 'Em Roll and last week's Hole In One, was in the high $15K range. But many econocars are now stickering in the $17-$19K range as of this season like the Kia Rio, Honda Fit, and even a Chevy Spark. I'll bet in a season or two, there won't be any more sub-$16,666 cars remaining, so Dice Game will almost exclusively be played for cars in the $21-$26K range.
Keep in mind that as of Season 11, there were no more sub-$6,000 cars ever offered, the cheapest being a Chevette in a playing of Double Prices that was $60XX. Seasons 8 and 9 had a high inflation rate compared to other seasons due to the second OPEC gas shock, so its not surprising that 1980 was approximately the last time that rolling a 5 would have required a decision.
In addition, the hundreds digit also had some pricing logic to it during the last few years of the four-digit format, where going higher on a 4 was usually wise (unless if it was a stripped Chevette).