I can't remember seeing a web shop that does IBAN/SWIFT transfers (apart from one or two small-time ebay sellers). I pay via wire transfer all the time within Germany, but outside it's credit card or paypal (and even the latter quite often requires a credit card transfer for that).

It's not a big deal for corporate / professional deals with largers sums, i.e. a monthly €49 subscription. But if you're running some kind of browser game and want to get one-time €2.99 payments, you'll have to deal with a rather different demographic. Have yet to see an internatinal (at least pan-European) service that provides a good solution for that. Most of the time you have to cobble it together from all different local providers, and a lot of them look quite fishy to me (and that's saying something in that market).