The gist of the price difference is simple in my opinion!
The exchange rate of the dollar has dropped dramatically in relation to the euro, the last couple of years. This makes the dollar price (when converted from euros) seem high when compared to the price at sites which are dollar based. Prices are generally set for the North American market, in dollars, and when the dollar falls, the euro prices are generally not adjusted to reflect this (an easy profit!).
The solution is to buy your software from dollar based sites and have it shipped to you in Europe. You will have to pay VAT and sometimes an additional surcharge for customs inspection (as in NL) at delivery. If you add this amount to the original purchase price it is still generally cheaper than when bought at a euro based site!
Less expensive is just downloading the software if possible, thereby avoiding the customs surcharge. Sometimes the extra VAT is also skipped because technically you've bought the software at a company in the country offering the software. These companies generally have no fiscal accountability to foreign countries and if you don't declare the purchase yourself, your local Treasury will not know of the transaction and you won't get the VAT surcharge!
Good luck with your software purchase! By the way, buying both iWork and Office2008 for Mac is not very economical because both suites offer pretty much the same functionality. It's better to choose which fits your needs best. You can "test-drive" both iWork '06 and Office2004 (to date they still don't offer a test drive version of Office2008!) on all Macs (are part of the pre-installed software) for 30 days, so comparing is easy! NeoOffice can be tested for an indefinite period, will install free of charge and is handy to convert documents offered in ".odf" format to ".doc" format and back. So I would strongly recommend you trying NeoOffice too, to make an informed personal choice, geared to your own situation and demands! Who knows, it might save you some cash which you can then use for other interesting software!
Lots of luck
Hil