The best deal on ReplayTV was when they started liquidating the older 4500/5000 units about two months back. They sold for around $350 including a lifetime subscription. Plus you got a unit that supported Commercial Advance, and Internet Show Sharing, something the newer 55xx units don't do.

Refurb and new 5040 units are still available at Replaytvoutlet.com. They now come with the 3 year activation, instead of the lifetime they offered recently. Still a good deal.

Newer units could be as cheep as TiVo as well, if they did monthly fees. Right now, the $500 for a 40 hour includes a 3 year subscription. After that, it's $12 a year.

TiVo $12.95 * 3 years = $466.20

All depends on how long you keep a unit I suppose.