My antenna is at 33' with a simple roof bracket and 10.5' chain link fence top rail mast from the home center, ca $11. There are lots of other options for gaining height above your roof - tripods, eave mounts, wall mounts, telescoping masts, etc. Look here
http://www.antennapartsoutlet.com/ - not an endorsement, but I've bought mast parts from them and they ship fast with reasonable shipping. There are other places on the net that sell this stuff too.
There are also tree mounts - pick a suitable tree and lop the top 5' off, strip some branches and that will get you way above the tree line. Stephanie posted a good pic of a tree mount in a recent thread...
And, there are free-standing towers and masts. Lots of options.
But the main thing is to look at the behavior of the signal strengths as you gain height. If you get a lot of gain for a modest increase, then you can think about it some more. All this stuff will be a one-time cost that should last for decades, so when you divide the time trouble and money over such a long time, it seems less daunting.