I did a quick search. Found one being sold by a private party with 82k miles for around $12kUSD. All maint. records, etc. w/Premium Pack.,alarm, tint, rims.
If the markup is 30-50% more in Australia and with a dealer's markup, about $18k would sound about right depending on the options included. Maybe you can get a warranty since it has less than 100k miles.
Most of the '95 525s I saw had 160k-190k miles. To find one with only 60k miles is very unusual. Averaged over 9 years would be less than 6k miles of driving per year.
I still would have the car check by another dealer or independent mechanic that could tell you the exact condition of the motor and its components.
2004 E60 530is, Delivered 12/12/03, TiSilver/LGrey, PP, SP,PS, PDC, ACC, FRS, Step, Xenons, clear bra, body colored rear inserts. (Retired, 1983 henna red 320is)
2004 Corvette Z06 Commemorative Edition