That is just to condition you to get accustomed to eventually having to buy it first before they let you know the price.
Which again is just to condition you to accept the fact that next they will be able to increase the price on your existing completed purchase each month for rest of your life.
It's only in the best interest of the consumer, it's not an evil tactic.
I'm pretty sure that's illegal in a lot of places. I know some stores have the "if you have to ask you can't afford it, boutique" vibe going on, but they do actually have to put the prices somewhere.