If you'll be using it daily then I'd consider the data used on your cellphone plan. You can get an Onyx Plus from Best Buy this week for $65 with a vehicle kit. I think the subscription will be slightly more for the sat radio vs the internet radio ($15 vs $20 or so, I think) but for ≈$5/mo you don't have to worry about your data plan.
Or go on EBay. You can find GREAT units on there for a really cheap prices.
A Stiletto 2 with car and home docks will run you about $200 or less+subscription. That is an awesome price for a unit that can record 100hrs of content, and be moved from inside your house to your car easily.
There are alot cheaper units on there as well. The one mentioned above I am sure is on there. And you could get it cheaper as well.