Alternatives to buying a repair stand? I'd like to buy a repair stand, but I can never seem to convince myself to drop the $100 minimum it seems I'd need to spend.  Has anybody had any success building a stand themselves, or is it worth it to just buy one?
As a number of other posts have pointed out, your best option is to get yourself a proper repair stand. They are not that expensive, and you will find that you and your friends all get good use out of it. But, if you are determined to do it on the cheap, here are a couple of techniques that worked for me before getting a workstand:


Turning the bike upside down - this is really simple and requires no additional purchase. You may want to look at putting some form of drop sheet down underneath the bike both to protect the saddle and handlebars, and to catch drips. This works well for pretty much any work on the wheels or transmission.
A bike storage rack or car rack - obviously these are already designed to hold a bike, and you may already have one to hand.
Suspending the bike with rope - If you have some overhead attachment points, this can work, however it is not going to provide an immovable mount for the bike - you will still need to hold the bike against the force of your tools when fastening and unfastening things. A trick to be aware of is to use two suspension points overhead and two on the bike (head tube and seat tube) otherwise the bike will spin in the air.