I like cheap too :-) I was using an old android phone with the
ip webcam app for a while until we had to call it back into service when another phone was broken. Then I bought a $3 webcam and currently use that with
yawcam software to make it an ipcamera for HG (I have a feature request to allow windows USB cameras in HG). I just use these in the house when we go on trips for reassurance everything is okay at home.
I'm interested in a "real" outdoor system too but wiring will be difficult at my house. The
Netgear Arlo cameras are interesting, but expensive, and from what I could gather (while standing in BestBuy debating an impulse buy), they aren't too "hacker friendly". If not aware, they are weatherproof, HD, completely wireless... battery powered and some RF to a hub. They only record when motion detection wakes them up.
I was thinking about a cheap trail camera mounted to tree aiming at house with an EyeFi card too :-)