Going back a little farther in 1990 I paid $7,794 for my new 1991 R100GS. $7,794 in 1990 converts to $17,604 in today's dollars. The new R1300 that will sell for around $25,000 well equipped (which would be $10,600 1990 dollars). But other than the letters GS, shaft drive, and boxer engine layout, the two are not even close to be comparable. Power, braking, efficiency, lighting, gear box, durability, handling, tyres, on and on are all vastly increased or improved.
Moto Guzzi's V85TT would be the closest comparison to a 1991 GS and even it has way better brakes, handling, lighting, more power, ABS, TC, cruise control, etc. and it lists for $12,000 or only $5,300 dollars back in 1990.
New motorcycles are far, far, better now than they were in years past and they don't really cost much more in real money, sometimes even less.