I guess the main reason it surprises me is because you can get a TivoHD for $200, and add your own external hard drive. I just checked, and my Series 3 (which admittedly has more space than the TivoHD) with a 750GB drive gives me 131 hours of HD space (and 1244 of SD). You can get a 1TB drive and a very good enclosure for $200 on Newegg, and then you've saved $200.
I agree. I actually just replaced the internal drive on my TivoHD with a 750GB drive using
WinMFS, costing me under $100, with over 100 hours of HD space.