Barrow is pretty easy to get around without a car, it isn't that big and if you don't mind walking. If you need to travel further distances, the taxis (at least when I was there last, over a year ago) were a flat rate of $5. I think, though I have never used them, the local "tour" companies are generally just residents who take people out to see the bears. They normally have other jobs, and do it as a side business. I would think they would do it anytime of year.

If you do find a local guide/tour, please post. I might try to go up there again either this year or next summer.