the next best thing, I guess is to create a separate page for each "Item" that was to go in my iFrame.
That is a much, much better way of doing it. Navigating in iframes has many drawbacks and is not a good idea unless you have special, unusual requirements.

The only problem is that it makes it so that all the logos and graphics have to load on the click of every button
Assuming they're common elements, they'll be cached, you won't get more than a flicker of page updating. This is how 99% of the web already works, you don't have to worry about it.