Old Reliable, aka Forever 21, currently has some boots in stock that I think would work well for anyone wanting to put together an Idris costume. I'm vaguely stuck between Chestnut and Olive as the best color.
Faux Suede Combat Boots - UK site, GBP 21.00
Faux Suede Combat Boots - US site, USD 25.50
Faux Suede Combat Boots - EU site, Euro 26,40