Strobe tuneres are expensive, running at $200 for the lower priced ones. But they are precise and are used to set intonation much closer to perfect than your regular sharp/flat tuners.

Luckily most guitar techs have such equipment in their shop, and it won't take one much more than 10 minutes to fix your intonation. So, I estimate, the price would run at 20-30 $$ tops and the job likely done on the spot.

Though if even that price is over your head, your ear is then the best bet. I found it impossible to set intonation using a regular tuner, and personally match it by ear, using procedure similar to one posted by Ren.