How much Apple will cut my revenue from selling items (e.g. shirts) in an iPhone app?

I'm developing a "free" iphone app for selling shirts based in an Asian country.
The payment method is by credit cards or wire transfer, not by Apple's in-app purchases.

Does Apple allow this kind of app in their store?
If so, do I have to share revenue with Apple?

Gilt also sells items online in their app. Do you know what's Gilt's business model?
Do they share revenue with Apple?

AFAIK Apple don't allow you to have "In App" purchases without using their system and giving them their cut. Doing so is a ToS violation and could get your app pulled.

As far as I can work out you can do a simple link to a web page from your app.

Even Amazon had to comply

http://www.computerworld.com/s/article/9218629/Amazon_caves_to_Apple_drops_Kindle_s_in_app_button http://www.pcworld.com/article/227899/apple_inapp_purchase_policy_has_consequences.html http://www.pcworld.com/article/227899/apple_inapp_purchase_policy_has_consequences.html (Disclaimer - I am really not involved with Apple/Mobile business so may be talking rubbish!)

Apple in-app purchase is only for (and required for) non-tangible goods. For that, they get 30%.

IF you are selling tangible goods (shirts, etc) use other services like braintreepayments or zooz

The TOS for apple is clear that IAP must be used when selling virtual goods, and cannot be used for selling tangible goods.

eBay will sell about $5B of merchandise this year via their app, without giving apple a cut from the sales.

While apple can always change the rules, under the current ones, you have nothing to worry about.

I can't give you a 100% answer from experience, but Amazon has an app for the iPad, and there is no way Amazon is giving apple 30% or anything really. They don't have such big profit margins and would use a web app instead if they were giving up a percentage of sales.

I know recently (a few months now) Apple changed their terms, and this is no doubt why you are worried. At the time I spoke to Apple and couldn't get a straight answer, however I think comparing to what others are doing might be the best evidence you can find.