The problem with your website is that it takes too long to discover whats available or I am doing this wrong.
For example if you have no ES44acs then the engine image of the ES44ac should be grayed-out. Otherwise I spend too much time click at each image to find that nothing is available.
Just a suggestion
I figured out a way "around" this - kinda: I go to "Advanced Search" then choose the category in the drop down (e.g. Trains/O Gauge/Lionel/Locomotives/Diesel-Electric) and then just scroll through what they have.
Not ideal, but better than clicking on each individual icon and then going back when nothing shows up.
Hope this helps...