I think the common idea that kits are cheaper on the internet is a little inaccurate. I can only speak for myself, but the nearest Hobbytown USA to me has kit prices that are, at first glance, higher than the popular on-line kit sellers. Until you factor in the shipping that is. Then the price is just about the same. The situation improves slightly if you order multiples of the same kit on-line, but not by much.
The real difference is in inventory. No brick and mortar store can possibly carry the inventory that is available on-line which is literally everything! Again, speaking only for the store near me, the kit selection there is minimal and they are slow to re-stock supplies that run out.
And there lies the big advantage that the internet has over at least this one local shop.