I don't think the 25 year old rule is anything to worry about. If you're after a 2002 model FD for example, they won't be eligible for import until 2027. By that time, all the good FDs will have dried up in Japan anyway. I've heard stories about fastidious owners of so-called "bonsai" cars (low km vehicles that never get driven) holding back for the 25 year onslaught from the US, but will there really be that much demand by then? By 2030, all new cars will be electric. They will be cheaper and outperform anything available today. Petrol prices will be through the roof and parts for old Mazdas will certainly be thin on the ground.

Collectors in the US desperate enough for low km stock cars are already buying up Japanese cars. They are just having them stored in Canada (where you can legally import all FD models right now) and going up to visit and drive them occasionally. They will then bring them south into the US when the 25 year rule is triggered. This is part of where the drive in Skyline prices has come from.

The recent price rises in FDs in Australia I think is driven more by local factors. Second hand car prices in Australia have increased 30% across the board. There are few new cars available. People have been bored in lockdown dreaming of cars. People have reportedly been taking advantage of accessing super early in order to buy toys. Even if you acquired a car at auction in Japan right now, there will likely be significant delays in getting them shipped and complianced. All factors which have contributed to price rises. There is also a new breed of owners who have become interested in the FD as a result of recent nostalgic popularisation of the cars in motoring media and on socials.

You may have read stories about JDM car prices going crazy in Japan (particularly GTRs and Supras). While there have been some very high prices at auction in Japan for ultra low km FDs in Japan, this is not necessarily seen in moderately driven cars and RX-7 prices have not risen to the same degree as Nissans. I have been following recent auctions and seen quite a few pretty good examples of Spirit Rs or Type RS cars with around 50,000km and they have been passing in with zero bids at prices much lower than cars in Australia are being advertised. There was a stock standard innocent blue mica Spirit R with 55,000 that passed in 7 times at 5.35 million yen. This works out to be around $90K landed, but was a much better example than the Spirit Rs advertised recently for much more.

This leads me to believe you can still get better deals at Japanese auctions, if you are prepared to wait for the car...and the car is much less likely to have a tampered odometer.

My 2c.