Cheap DVD Recorder that can be upgraded to use HDD

I was wanting to buy a DVD Recorder with a HDD, something like the lite-on LVW5045 or Mustek DVD-R580, but then I noticed a local shop selling the Mustek DVD-R100 DVD Recorder (no HDD) and I got to thinking if maybe it could have a HDD added, or if there were any consumer DVD recorders that are shipped without a HDD installed, but could be modified to use one for full DVR use. Now I would expect some manufacturers would make one mainboard and use it in various models with and without hdds, maybe with a different BIOS, etc. So in theory I could throw in a 200GB HDD and maybe update the firmware and have a low-cost solution.

Does anyone know of any brands/models that are suitable for this kind of mod? I know a lot of old DVD players (sampo, hiteker, etc) were modded to play files from HDD, but I also want to record to it (fully functioned DVR etc).

Any suggestions?