Many doormats can be bought for under $10 and then retailed for $40 or more. The challenge for you as a sublimator is that floor mats may be larger than what your printer can handle. But you don’t have to do full-bleed images with floor mats, so that may not be a problem. It does help to have a heat press larger than the floor mat, but you may be ok with one that is not. Simply experiment with the pressure settings to ensure a good image without any press lines.