where do you buy your swim stuff?

Gazelle Sports in Grand Rapids has a nice selection of swimming and other tri gear.

Dexter Bike and Sport, my local Tri shop

but if I need specialized swim stuff, it is hard to beat Different Strokes (http://www.different-strokes.com/).. The have stores in Livonia, St Clair Shores, and Auburn Hills.

eBay!  I have purchased some amazing NEW stuff from this seller:

http://shop.ebay.com//m.html?_nkw=&_armrs=1&_from=&_ipg=&_trksid=p3686

Including an awesome 2 piece Zoot tri swim suit for my daughter.  I have found that the winter months are the best time to score tri stuff, cheap, on eBay.

I've had really good luck with SwimOutlet.com. 

Different Strokes!

Dunham's and MC Sport for most of my basics, ebay for wetsuits and more tri-specific items.

Not to start a debate, but I like to spend my money locally. On most things, even though I may pay a little more, the free advice, customer service, and more importantly, immediate access MORE than makes up for any price differences. There is nothing worse than needing something right before a race, and not being able to source it locally because all the local stores are gone. Example, a few years ago, I managed to explode a chain and destroyed a rear derailleur the evening before a race. I called my LBS, and explained the situation. They stayed open, waited for me, and fixed my bike while I waited. I wouldn't have expected, nor would it be fair to expect that kind of service if I wasn't a regular customer, and was calling for repair to my "internet special" bicycle. That alone buys them my loyalty.

Different Strokes or The Varsity Shop in Birmingham.  You can always find suites on sale at Different Strokes.  And since you probably arent swimming competitively (i.e. high school or masters) and only training, all you need is a cheap training suit and not a race suit. 

this  ^^^

I'm all for buying locally, but if the stores don't carry the suit I need (read:  something that actually supports the girls), then I gotta go where I can find them.

If you're in the Ann Arbor area and like to buy from a local shop, I go to Sun & Snow in the Westgate shopping plaza. They have a wide range of goggles, pull buoys, paddles, and several racks of swim suits, usually with a sale rack.