Try Adjusting The Cost of Base Items?

Basically make all of these the same cost [400g]: (Some already are)

Adjust the rest of the items which build from these to match the increase or decrease in price.

This stalls out the early portion of the game more, which will help cushion massive snowballing, while keeping matches generally the same length they currently are. Maybe it's not a flawless idea, but I think it's a fairly risk free with little to no possible balance issues down the road, and it will help the game feel more like a strategic MOBA and less like an out of control ARAM.