If it were me, I would invest in a mountain bike compact triple crank set and the tools to do the job. It sounds like the crank would be more that you want to budget, but the tools could be cheaper than what the dealer would charge you to do things.
Why are you advising the author to throw money in the toilet? Your advice is very expensive compared to changing the chain rings. The mountain bike triple you recommend can get down to a 22 tooth inner ring. He currently has a road triple crankset with 130mm bcd for the outer and middle positions and 74mm bcd for the inner ring. He can put a 24 tooth ring on his current crankset. There is so little difference between a 22 and 24 inner ring that its not worth talking about. You're advising him to spend an extra $100 to get two less teeth on the inner ring. Big waste of money. Cheapest and easiest is for him to just leave the outer and middle rings alone at 52-42, and replace the inner ring with a 24. $15 plus the labor of changing the inner ring. Or he could spend the extra $60 and change the outer and middle rings to 48-38 or 46-38 for fun. But changing the crankset is throwing money in the toilet and flushing it down the drain.
For fun I went to Amazon and typed in "Sugino chainrings". Came up with a $15.23 24 tooth 74mm bcd ring, $21.70 for a 130mm bcd ring, and $33.25 for a 50 tooth 130mm bcd ring. If you looked closer I'm sure you could find other tooth counts for about the same price as listed here. So for $70 in rings the author can have a 50-38-24 crankset using the crank and bottom bracket he already owns. Minimal labor to change rings. Your idea of a new crankset would not get within $100 of the $70 listed here. And not have much better gearing either. What is the point of spending more money than you need to?
Also do a search on Amazon for "Vuelta chainrings". Vuelta and Sugino are comparable. I came up with a $79 total for Vuelta 48-38-24 rings.