All good advice, and I'll chime in with my experiences on actually having ran outdoor cabling.
Plain old Cat5 has an amazing ability to tolerate the elements. In order to get my internet to work I had to cover roughly 300 feet or ground to get to the provider drop point.
In order to accomplish this a hole was drilled through the wall and a cable ran from my router through the hole to the outside, up the wall to just under the eave then along the house. From there the cable ran up into a tree, draped over a branch and then ran across the yard as an aerial run to a utility pole at the back of the yard. The cable was wrapped around the pole about 8 times (Making a great coil) and from there ran across the property to another pole, wrapped around about 6 times and then out to the roof of the building where the drop was.
That unprotected, exposed aerial run of indoor Cat5 lasted over a year and a half and was still working fine when I left. I ran WoW raids on it, shot zombies in L4D and tried out SWTOR.
That cable survived birds sitting on it, ice storms, rain and a hell of a lot of UV light. Dont underestimate your plain jane Cat5, it can stand up to a hell of a lot. If you can keep it mostly protected along a house I wouldnt hesitate at all to run the "cheap stuff" where you need it.
I had worked up plans to run a new cable and put in conduit. Again, in true Bubba fashion my conduit was going to be garden hose. The wife shot that down fast, she didnt want a garden hose hanging in the air all across our property but I thought it would have been funny as hell.
Point there is you could work up a really cheap conduit by using garden hose and painting it to match the side of the house.