Replacement heads (band razor carts) haven't been made in some time, but can occasionally be found on ebay if you're lucky. From all reports, not the best shaver to begin with, so you may not want to make the effort.
I hope the odd one pops up from time to time seeings as I just bought a Techmatic. I managed to get a couple of cartridges from B/S/T so I should be OK for a little while.