I often boast that I have never had a request I could not do, and this is true.  This brings up some weird requests from people trying to challenge my skill.  Trying to remember some of the weirder ones, I have made:  A hot dog with ketchup and mustard, a twin towers hat (pre 9/11), a bikini for a girl, a sweater for a girl, a bra (all clothing is wearable and fitted), Ronald Reagan, Madona,the person asking for the balloon on a few occasions, a beautiful woman for a man with his wife, a girlfriend for a boy with his girlfriend, a wolverine from x-men slashing through a football(soccer for anyone not in the us) for a game that took more than 100 balloons,  a liger, unicorn, skunk, the Olympic symbols, a shark eating a man and many more I'm sure.  I think the weirdest one of all would have to be a toilet though, especially because I was making balloons at a restaurant.
All of these request I made up on the spot and to the satisfaction of the customer, usually I just get "wow, you really can make anything".

Parcival, you answered a question I was wondering myself in one of your posts.  Can you busk during the week?  I expected during the times when children are in school the balloon business would be a bust (excuse the bad pun).  I have some magic acts aimed for adults I am going to try to fill in with at these times.  Things like fire eating, glass eating, a razor blade swallowing and slight of hand act, real don't try this at home kind of stuff.  Is it bad during the evening when children are out of school though?  I'm sure it is somewhat location specific, I'm just curious to hear other people's experiences.

A dollar regardless of how many balloons I use.  Generally if it is  really fancy I get a tip anyways.  When I go to Florida to do street performing and busking I will charge more for complicated balloons.

I make big stuff and little stuff and I currently only ask a dollar per balloon.  I love making the big stuff, its fun for me.  The only problem is if you get a big line and your making fancy stuff it can take a while to get through the people.  Also once you have made the fancy stuff you cant really tell someone no.  Most of the time when I make a fancy one people tip extra for the work also.

I am planning on moving down south and busking with balloons and performing magic and fire eating on the street.  I am from America and have been looking at the laws on doing this.  It seems in America you do not need a license to perform or sell art on the streets, it even lists sculptures under art.  A balloon animal is a sculpture, even though it may be a different medium than we are used to seeing sculptures.  Making balloon animals is also an art and a performance.  Bearing this in mind, as long as I am interpreting the law correctly you can legally put a price per balloon on your creations.  

Now as far as it being a lowly form of balloon twisting and only for desperate people I don't think that is the case.  I know whenever I am on vacation or at a festival I always look for the street performers.  I find street performers incredibly entertaining and I always tip when I can.  The way I look at it is where else can you get live entertainment so cheaply, and at the same time be so close to the performer.  When it comes to balloon artists you even get a work of art made just for you.  I look at balloon art as a real art.  Imagine if you were a painter instead of a twister.  Do you know any other kind of artist that will give away art custom made for you for a dollar or so?

Lastly, I have found a lot of people don't tip not because they are cheap, but because they don't know any bettor or forget to.  Many times working at fairs the parents give the kids the money to give to me.  They stand patiently waiting for the balloon and then run off with the money as soon as they get their balloon.  In a few seconds their parents send them back with the money to give to me.  This is a great example of knowing your supposed to tip but forgetting or still having to have someone remind you.  Balloons bring out the kids and innocence of all of us, even the adults.  So have a sign or a pin reminding them to tip.  This way you don't have to ask for donations if you feel uncomfortable with that, but the people are still reminded to do so.