I actually bought my modem, Toshiba PCX1100. After one year it'll pay itself off. Paid $150 for the modem and got first month free. I save $10 a month because I own the modem. The only thing that I am scared of is AT&T's service. They bought out mediaone and they can't keep roadrunner because it's a conflict of interest or something like that. AT&T has to keep the contract that mediaone had with roadrunner till the end of 2001 and then they have to dump it. Then we get AT&T @home crappy service. I actually had it before and it sucked. But they are telling me that by then you should have a choice on who you want to be your service provider. I'm not holding my breath on that one.
One more note is that the industry standardized the cable modems. Just get a modem that has the current DOCSIS standard.