Some 2008 (and even 2009) models used excessive oil; a condition addressed by installing re-designed piston/ring sets, or aftermarket pistons (685 cc or greater displacement big-bore kits).
Then again, some DIDN'T use excessive oil.
No way to tell which population your prospective bike belongs to without prior maintenance history, or . . . riding it and finding out for yourself.
I'd say, you might GO FOR IT. Even if it uses a bit of oil, you can add lubricant until you are in a position to fix the situation.
BUT . . . KEEP AN EYE ON THE OIL LEVEL! Give the oil time to settle in the sump after operation, and inspect the sight glass with the bike held level (at least, at every fueling at first, to get to know the bike's nominal oil thirst). OIL STARVATION RUINS
cylinder head cam journals; no convenient nor inexpensive fix for this situation (replacement cylinder head most likely repair).
Depending upon preparation of the bike before storage, you might check out the, "Carb Overhaul" thread on this website; drain and replace all fluids; check tires for condition (dry rot likely); and . . . inmates probably will suggest other maintenance/age indicators worth examining. Surely, you'll be admonished to replace the "doohickey" (idler shaft lever) with aftermarket item and "torsion" spring; sound maintenance for a KLR650 (not so especially urgent and critical for one of the vintage under consideration), but . . . not so urgent as some suggest, in my humble opinion. Some KLR650s spend their entire service life with stock doohickeys, some suffer catastrophic failures (not so much for 2008 and later editions).
Just for your consideration, KLR650 production has ended with 2018 models; sounds like you have a chance to acquire a COLLECTIBLE motorcycle!
DISCLAIMER: My opinions ONLY above; no infallibility claimed!