Im looking for a good running gag. Ive been looking for a flower that continusly grows throught the show. Does anyone know where this can be purchased?

What you are describing, would be extremely expensive. Most blooming flower effects are not cheap. You may want to consider a Lota Bowl type routine, instead. Penguin offers two types of Lota Bowls:
http://www.penguinmagic.com/specialorderproduct.php?ID=5191

And:

http://www.penguinmagic.com/specialorderproduct.php?ID=7382

ok thanks.

Are there any others?

I don't have it yet but (soon, though, I hope) try 'Endless Rose.' Penguin has a video of it and it may be what you are looking for.

Mouth coils!

What do mouth coils have to do with a running gag?

I guess you can pull the coils out of random spots throughout the routine...

A special fx board?

Have the person talk at random times. That could be a running gag...

How much do those fx boards usually go for? I can't determine which brand is a good quality and what I would expect to pay for a good one.

How are you actually looking for the information? Personally, I don't know of any "brands" of these things other than Axtell (well... I suppose you could count Martin Lewis's "Cardiographic"... sort of... maybe... but not really).

The Magic Drawing Board is about $115 and the Special FX Board is about $100, excluding shipping, etc. Now, both of these boards require you to hold them in order to animate the images; the most efective running gag board, though, would be the remote control version of the Magic Drawing Board, which will set you back over $1200. I'll stick to my Change Bag gags and novelty wands for now.

Those boards are quite expensive. I've been looking into buying one for some time now. http://www.axtell.com/mdb.html This is a quality one that I'm looking into getting. Just a little over $100, so it's not too bad. (Edit) I see that TheCaffenaitor beat me to it.

As for running gags, mouth coils would be a good idea. I personally use water juggling as a running gag. That and balloon animals (the possibilities with balloons are endless). I've also just had a stuffed rabbit on stage before and acted like it was a real bunny just sleeping. The kids got a kick out of it because I had rigged it so that the bunny could move (through the use of a remote control). Sadly though, it burned in a fire, and I have yet had the time to replace it.