+1 with NJ.
Other than that 30,000 miles, (50,000klm) might be considered high milage. Thing is there are a couple of guys on here with 60,000 +miles. Maintenance is the big issue, if the Owner has kept up on that then mileage is relevant to price and condition. With these bikes a top end refresh, (do check the con-rod freeplay and little end for wear), is usually all that is needed, Piston/rings front guide and the cam-chain, Pistons and rings can b got for a reasonable price.
if a bike ha been sitting for number of years then it is the things like brakes/caliper/MC/hoses, gauge dampers and electrical connections that will need to be replaced/upgraded and gone through to make it reliable and safe
You have had bikes, so some of this you already know, but the cost of refreshing a bike that has been sitting for years is going to cost
Do ask for any help before buying anything and we will point you in the direction of the cheapest where possible and the best quality
Clock on my, 83. Original mileage, 42,000klm +. still going strong
Most bikes now will need their front cam chain guide replaced if the PO hasn't a;ready done it. They de-laminate. I;m of the mind when the bike sits for a long time, (years), the front guide isn't being covered in hot oil and they get brittle and shrink enough to de laminate. Maybe if a bike has been ridden regular the guide may not be a problem. While in the top end replacing a cam chain sprudent
Charging Rotor needs to be rewound, Age is catching up with them. Do not buy an aftermarket one. Local member Jim does rewinds for a good price that undercuts the quality of his work. Regulator and Rectifiers can be replaced with Automotive Regulator and a bridge Rectifier, this will refresh the charging system, make it reliable and doesn't cost a fortune. In fact it is very cost effective, (maybe $180 for you US guys compared to several hundred going to a PMA), with piece of mind