As the article says, a TR3A, "in good condition," has a current market value of $13,500 to $18,500." I think the author may be close to the actual value at $18,500. But one could easily put another $10,000 to $15,000 into the car to rebuild the engine, transmission, exhaust system, etc., etc. So, I estimate that a TR3A in "worry-free driving condition" (ha! ha!)would be somewhere around $30,000 (high end). If you look at some of the prices being paid in England and elsewhere, that is a reasonable estimate.
We're talking excellent operating condition but not fabulous "show condition" here.
Some estimate that to completely restore a TR3A to "mint" condition would cost about $70,000. I don't know anyone who would go there unless they were absolutely "in love" with the car.
The January 2010 edition of Classic Motorsports (p. 39) says, referring to TR3, "Nice drivers can still be had for just under $20,000, and really good examples that could win a show or two only cost around $24,000 to $29,000."
Want to increase the market value? Just feature the TR3 in a feature film or two, as they were featured so often in the 50s and 60s, and the "market value" will rise dramatically. (My opinion.)
And, finally, I wonder what the market value would be in China today?