What you are talking about is digital signage. There is a lot you can do for a reasonable price hardware is the cheap and easy part. Well touch screen gets a little pricey.
Making the catalog's and being interactive etc will cost you unless you know flash and what not.
We are looking at getting into this as a wholesale supplier but we are not at the moment.
For your purposes all you need are a couple of cheap tablets that can run the latest and greatest flash.
Then you need to or sub it out have the catalog's made in flash. They can be as simple as click to change page or click to see more info on each product depends on you and your budget.
There is another option for what you are wanting. You could build new webpages in a secured area and pull all catalog info from databases or hard code it and just have the tablets on line through your shops connection. Just a second simple and cheaper thought but not as flashy (Pun intended).