Where can I buy cheap size 15 inline skates?

I need a size 15 pair of inline skates for some roller hockey. The only problem is I can't find any pairs that big anywhere, not even on ebay. The highest I've seen for inlines are size 12's. And if there is no place that sells this large of a size is there anyway I could take a pair of my DC skate shoes which have a flat bottom, reinforce it with metal on the soles, then bolt on the base of inline skates? I've seen this done but it was with quad skates, not inlines.