As the price of bitcoin transactions fluctuate on MtGox, so do the prices of my shirts at SquareWear.  Not that it changes anything, but I wonder what to root for, increase in price of BTC, decrease, or stability. 

Increases bring the cost down relative to people's native currency (they'll likely soon be under 2Ƀ), but might make people reluctant to spend.  Decreases in price may spur purchases (people wanting to spend while it still has value).  Stability may take the concern of relative value out of people's mind and allow them to make normal purchasing decisions.

For other businesses selling in BTC, do you notice sales differences based on the fluctuations in BTC price?  For BTC spenders, do you find your own purchases affected by Mt Gox price?

I personally would root for stability.  As Littleshop said, somewhere in the 6-8 USD range would be ideal.

Stable currencies induce people to spend more because they don't feel like their money is going to be changed in value between today and tomorrow.  It decreases hording in the case of deflation, and increases spending on ordinary goods in the case of inflation.

I also think that people enjoy the idea of spending currencies worth more than their native currency, and 6-8 USD plays into that well.  6-8 USD is also not so high as to discourage people from purchasing bitcoin.

Of course, I am not a economist by any means, and this is all just speculation.

Please post a link to your website so I can order some shirts.

If you need any electronics,  please order from me in bitcoins.
www.memorydealers.com

With the rally, our two shirts that are on sale are only 1.33.  They'll be under 1 coin/per shirt soon.  That's crazy, yo.