Make your own Bumper Stickers
Famously, Freedom of the Press belongs to him what owns one.  Similarly, Freedom of Expression could be said to be restricted when you can't find a bumper sticker that says what you want. 
Some three years back, I figured out how to make my own bumper stickers and have been "expressing myself"  (some would say making a fool of myself) by plastering my poor car with leftie bumper stickers



My wife is a minimalist and gets by with the one bumper sticker she asked me to make for her CRV.

If you want a closer look, here's a higher resolution version
, 120Kin size
Now that Kerry was 'defeated', I removed some so it looks a little patchy, but never fear, there's more to come.  Some new favorites:
Moral Values Explained: Sex by O'Reilly,  Lies by Bush, Gambling by Bennett, Torture by Gonzales.  
Any Idiot can start a War
Hey George, Send Your Kids to Iraq!

The bumper stickers I make are black and white (no color),  made on a normal laser printer (an old IBM/Lexmark 4029) on a special heat-resistant vinyl label material that can make it through a laser printer's fuser (where the toner powder gets melted onto the page) without turning into taffy and lunching your laster printer.  They are extremely durable (after 3-4+ years, they're as good as new if a little greyed from accumulated dirt).  I  generate the design using Corel Draw (though any middle level or better computer art software can be used).

So, you'll need:

The label material

Comes from a great operation on the West Coast,  RippedSheets.com (a ripped sheet is a printing trade term...in the trade, the stock (paper, whatever) is made in enormous sheets or rolls.  An intermediary jobber would cut or section those big sheets to turn out ripped sheets) that sells specialized label material.in small qunatities and sizes.
http://www.rippedsheets.com
I use their #102600 Outdoor Waterproof White Vinyl Super Permanent Self Adhesive label material
http://www.rippedsheets.com/laser/outdrperma.html
I buy "legal" size sheets, 8.5"x14".  One sheet cut into thirds down the length of the long side yields three 2.75"x14" bumper stickers.  Alas, it isn't cheap; the legal-sized sheets cost $3 to $6, depending on the quantity you buy.  I would suggest you buy no more than you can use in 2-3 months, as the backing paper that covers the adhesive side can get difficult to pull off if it sits on the shelf longer than that.

Designing and Printing the Bumper Sticker

I'm not going to tell you how to do the artwork, but I do have some pointers

Applying and removing your Bumper Stickers

Miscellany

All information, images and snappy bumper sticker text herein  are copyright and remain my possession.  Use them freely, but please credit me and give a cut if you make money off of them....