Asking once and being denied is one thing. Asking multiple times to see an item and being told no, it's too expensive for you. Not OK. It doesn't matter whether it's Oprah or not. The sales assistant was rude and no form of verbal or mental gymnastics will overcome that. Oprah is a public figure who generates strong feelings. That being said, rude is rude. No one deserves to be treated rudely.
How many stories have we seen on here where people, mostly women, go to car dealerships and are rebuffed because the salesmen don't think they are serious. That purse cost the same amount as a car. I haven't seen a single poster say that the car salesmen are in the right to treat potential customers like that, so why is it ok for a retail salesperson to treat someone that way?