You don't have to spend any money on this, just follow Sheldon Brown's Cold setting directions.http://sheldonbrown.com/frame-spacing.html#spreading; while this procedure is advertised to spread the stays for wider hubs, it can also be used to straighten a frame; something I recently did with my old Bontrager; I grabbed my Bonty to ride with my son and noticed the rear wheel was canted toward the left chain stay (I can't imagine how it occurred unless it was damage from a crash about 10 years ago, but you'd think I would notice it before now). Anyway I flipped the tire and indeed it was still canted toward the left chain stay. This means there is a dish issue also because if it was just the stays flipping the wheel would make no difference. Anyway I used the string method to double check and indeed the stays were out of alignment.

For this/my method, you need a wheel that you know is straight (you can also use the string method but this is faster). Your bicycle looks like the wheel is canted to the left looking at the brake center. This means the stays are canted to the left. You'll want to bend the stays to the right. Thread a 2x4 through the stays per Sheldon Brown. Since you want to move the stays to the left, you will want to spread the right stay and narrow the left stay. As an example, spread the left stay about 2mm (difference between the present measurement and spread measurement). Then narrow the right stay the same distance until your hub can slide in (not to wide, not to narrow). Here's were the straight wheel comes in; mount the wheel and see if the stays are now straight or they need more bending. Once the frame is to a point where the wheel looks straight in the stays, re-check with the string method. This is what I did and it worked great, just make sure you remove the wheels and either remove the rear derailleur or place a piece of 2x4 (or similar) adjacent to the derailleur to protect it during the bending process.