Yes, and there are several magic items that do. It's probably best to back-figure from those as the default magic item creation rules don't always give good results for unusual items.
Check out (on the better PFSRD):
The gloves of elvenkind are the best compare (in fact, you probably should just use them and move along). Cloak/boots are also +5 skill items for 2500.
Now the gloves do Spellcraft and Concentration, so you have to calculate that using the "two effects on one item" cost - like Gloves of Swimming and Climbing are 6250 gp, which is 2500 (Swim) + 2500 (climb) + 1250 (50% of the second power combo cost).
Therefore the 7500 cost of these gloves is 3750 (Concentration) + 2500 (Spellcraft) + 1250 (50% of the second power combo cost). So Concentration bonuses could be said to be 50% more expensive than a skill bonus (bonus squared x 150 gp). Also, that bonus is only for casting defensively - I would assume that caveat would make a flat "bonus to Concentration checks in all circumstances" much more expensive. I have no basis for this than my opinion, but I'd go bonus squared x 500 gp - it's clearly intended to be less than a stat or save bonus, but more than a skill bonus.