Even if I already own two modems, the bill would increase for having two modems active? Also, for the digital line... I'm pretty sure I can move my modem to any of the outlets I have in my apt.
Yeah, they will charge you for leasing another IP address on the 2nd cable modem. It is true that you could move it to any available cable outlet in your Apt, and probably most of the building in that case. The cable modems are allowed access by MAC Filtering, so the second modem would have to be allowed on the network, and at that point they would charge you for 2 separate connections.
If you are looking to extend your wireless range I would look at the Netgear WNDR3300. They are pretty stable for a consumer grade wireless bridge/repeater, and they are fairly easy to connect to each other using WPS. They are a little pricey however, and you would need two in order to bridge them wirelessly.
http://www.netgear.com/Products/RoutersandGateways/RangeMaxWirelessNRoutersandGateways/WNDR3300.aspxOr if you just need ethernet to reach the other location, check out Ethernet over powerline. Their speed and reliability have come along way in the past 3 years, but you still may have issues in an apt. I used a couple of these to connect a music PC in my detatched garage to the network in my home. They work pretty well, max speed for mine is 11Mbps, although I only see 5Mbps or so. Good enough for streaming music and most TV shows.
http://www.netgear.com/Products/PowerlineNetworking/PowerlineEthernetAdapters/XEB1004.aspx (these are a newer version that support up to 85Mbps theoretically)
