Only the old Series 1 SA (standalone) TiVo's that shipped with software version 1.3 or older will work without TiVo service. From what I remember you will get nag screens every time you press the TiVo button, and it didn't let you set recordings for more than 30 minutes. If you search www.dealdatebase.com/forum/ you might find some hacks to trick the older TiVo's into thinking you have service.

I think that the service really is worth every penny I've paid ($1047.25). My first TiVo I have almost had for 4 years the second is also most 3 years and the thrid is just over two years. The first one is a lifetime subscription and the others are monthly.

If I was buying a TiVo today I would find the best price on any size Philips SA series 1 TiVo that has the lifetime subscription since you can upgrade the space yourself.