I bought a Series 2 single tuner with lifetime service for $50. It has 80 hr capacity.
This would be a tough sell for limited manual recording. I recommend searching on eBay, and check "completed" listings, to see what closed.
Toshiba SD-H400, Tivo Series 2, Tivo HD, TiVo Series 3 THX, TiVo Premiere (All upgraded with extra HD goodness) and an XL4.