Moving out of my apartment on Sullivan Street, the one thing I'm really going to miss was the heated bathroom floor. Set to a timer, it was always toasty underfoot in the morning and at night. Ursula even liked to lie on it after her bath.
I inquired with the company that did the renovation just over a year ago and they recommended the product that they use in all their renovations: Warmup matting. While Warmup makes many products, their matting system rolls out and can be ordered to fit under any floor size, and is a great, easy addition if your redoing your bathroom floors (that said, you can also do other rooms in your house and use radiant heating to cut down your conventional heating bills).
I priced doing my little bathroom of 25 s/f and they sent back an automatic quote of $438 for the matting system. When I put in 100 s/f it only raised the price to $719. All that you need outside of rolling it out before you install your tiles on top is an electrician to hook it up to a higher voltage line and to mount the thermostat/controller on the wall. Radiant heating has come a long way in the past twenty years, and this is nice way to add a little luxury and save some money on heating bills at the same time.