Roof-Top Tower Alternative
Towers are wonderful. Best case scenario is a telescopic, then tilt-over. Only bad thing with a tilt-over is that while the tower is being tilted UP, the tower can bow if there's too much on the top. Telescopic's are great, if you can afford them. Most ideal situations are motorized, but if you can't afford the motorized devices, then you'll have to crank it up.
In my situation, with a fear of heights (never bothered me before; Since I hit the "50" mark), I start quivering with heights. So, I did the next best thing. Glen Martin 8' quad-pod. VERY reasonable; shipping was less than $20. Took one hour to build, but you must reinforce your attic. Luckily, a fellow ham had recently done his, and guided me through each step in person.
I'll attach a few pics of my quad-pod (which is now "populated" with several antennas), and the links to Glen Martin.
http://www.glenmartin.com/catalog/page14.html
Mine is the RT-832 (similar to the 936 in the pic)
Remember, you MUST reinforce your attic with the lumber matrix, otherwise you might lose the tower, antennas, and even the top part of your roof if you don't reinforce!
I think we spent under $30 for the lumber, much of which can be found in the remnants section of your favorite lumber supply source.