Most chip companies don't publish prices because they are useless to most of their customers. And by "customers", I mean people that buy chips in volume. For example, TI publishes prices at 1,000 units per year. If I buy more than that, I can get a better price-- and most manufacturers will buy more than 1k/year. But on top of the normal volume discount, I can negotiate a better price. Let's say that I want 1k/year of a part, I can usually get 5k/year pricing. I could also make a case for a "package deal", where if I need 1k/year each of 5 different chips then I could request 5k/year pricing on everything.
In the end, the price on the web site is almost never the price that I actually pay. Further, the price I pay is almost never the price that you will pay. Maybe you got a better price, or maybe I did. Either way, TI doesn't want us to know each others price because then we could use that as leverage to get a lower price.
The other thing is that these chip companies don't make any money selling small quantities. Their overhead is quite large, and they need customers buying large quantities at a time. The point is, they have no motivation to sell direct to the small customer. That's why there are places like Digikey. Digikey will buy large lots, divide them up, and sell them 1 or 10 at a time.
Some chip companies know that selling small qty is a loosing proposition, and they are actually better off giving them away-- if in "good will credit" if not actual money. That's what Maxim, National, TI, and Microchip do. TI actually contracted with Digikey for their sample program. If you ask for samples from TI, Digikey will be the one to ship it to you.
So, when buying specialized components in small qty you'll frequently be out of luck. The chip manufacturers won't sell it to you, and probably won't sample it either. The wholesale distributors won't talk with you for similar reasons. And Digikey and places like that won't help either.
One thing to look for is each manufacturer will list, somewhere, places that sell their parts. Sometimes it's a link off of the individual chip's page, or sometimes it is somewhere else. But check out that list. Most of those suppliers will be wholesalers who won't talk to you, but they might mention places like Digikey or Mouser. Failing that, you could email their main sales people and just be up-front about what you're doing and how much you will be buying and ask them where you should go to buy it.