Back to the future 2015 trainer foam?

Hi I'm new to the boards but I've been building props and costumes for a few years now. I'm beginning to make some back to the future part 2 Nike trainers. What I'm planning to do is to heavily modify a pair of Nike Greco Supreme, a style of boxing trainer that has the high top similar to the future nikes. I've been looking for a while now for some foam that I can make the soles of the trainers out of and also the MAG logo on the back but have come up empty handed. I've a feeling its the same foam used to make sports sandals. I've been looking for a place I can order a block of this stuff in order to shape the foam then stitch to the trainer. Can anyone point me in the right direction?

You may want to look into EVA foam, it commonly comes in 1/2 inch thick tiles which I think would be perfect for the sole.
They can be found at Lowes, Home Depot, Harbor Freight, even some Walmarts carry them though I'm not sure of a supplier in The UK aside from online sources.
They will be similar if not identical to the this:
Amazon.com: We Sell Mats 1/2" Thick Reversible Foam Interlocking Anti Fatigue Mat Charcoal Gray, Black, Blue with Borders: Sports & Outdoors

Hey thats awesome, thanks a lot for that, been looking around google and have seen a few example of what I'm after. Might not be the mint speckled stuff used in the film but its pretty close