Ornn Mini-shop Idea
https://i.imgur.com/FvjBt7P.png
The above image is not mine, found on Google, and I'm only using it to illustrate what I am talking about in case you aren't sure.
While at the fountain, players should be able to drag and drop items from the main shop to Ornn's mini-shop windows. Add a sixth slot at base, ... or hell, why not permanently? For the mini-shop examples below I am still going to use 5 for now. While the player is not at the fountain, the mini-shop shows items to build in grey or colored based on recommendation and affordability.
For example,
If I want my final build to be

I will most likely start with a Doran's Shield
out of base. Then by the time I have accumulated 500 gold, the mini-shop should give me the following options.

The only component item within this build that I could afford at this time but is not showing is rejuvenation beads
. I would do this because the mini-shop should show the most expensive options available. If in this case I wanted to purchase a rejuvenation bead I could either manually open up the shop and craft it from there, or I could craft boots, a cloth armor, or a sapphire crystal, then rejuv beads would be an option.
Lets say I decide to build a ruby crystal
and continue to play until we have reached another 800 gold.
I still want to be shown component items for the other items based on the most valuable items that I can afford.

Lets take a step back and say I purchased sapphire crystal
instead of the ruby crystal 
When i reached 800 gold, this is what I should see.

I actually noticed here that I was not factoring stopwatch
into my calculations ... we'll just assume that I have Perfect Timing.
I think I could go on, and I am sure there would be some interesting scenarios that I'm not taking into consideration, but this is the direction I think this should go.
into my calculations ... we'll just assume that I have Perfect Timing.