Meticulously maintenance with records can off set the mileage. I'm sometimes more concerned with low miles on a bike that has sat unused. In your situation a 90K mile bike makes sense, as a first bike you may not put a lot of miles on it, and if you do you can move to something newer with maybe no loss on the Strom. If you were a high mileage rider you'd be better to look for a lower mileage bike, they're plentiful.
Some high mileage maintenance you may look into if you keep the bike is steering head bearings, swingarm bushings, rear shock. I have 67K miles on my '09 650 and haven't done these things yet, I feel the bike will easily do 125K miles with just basic maintenance.
Not sure where you're located, but in the dead of winter it's a buyers market, don't be afraid of offering less, that bike isn't going anywhere for about 2 months. I've seen 650's with half the mileage and a lot of accessories going for $3K or less.
2009 Wee Strom ABS (current)
1987 Harley Low Rider Sport (current - with 205K miles)
2009 Aprilia Mana 850, 2006 SV650, 1984 Yamaha Virago 1000 (all sold)
Silver Strom Club Member #11
Wee Farkles: Russell Day Long Seat, Madstad with Moose Adventure Shield +4'', SWMotech Centerstand, 1'' up & back bar risers, Givi XS308 Tankbag, Aprilia mirrors, Framesliders, Fenda Extenda, Elka Shock.