All marketplace prices for an EU registered member include VAT.
This is wrong, for VAT registered companies located within the European Union!
Based on the Cross-border VAT EU directives (Cross-border VAT rates in Europe - Your Europe)
Selling Products to businesses
If you sell goods to another business and these goods are sent to another EU country,** you do not charge VAT** - if the customer has a valid VAT number.
You may still deduct the VAT you yourself have paid on your related expenses (goods/services bought in specifically to make those sales).
If the customer does not have a valid VAT number, you must normally charge VAT on the sale at the rate applicable in your country.
Selling Services to businesses
You do not normally charge your customers VAT. Your customers will pay VAT on the services received at the applicable rate in their country (using the reverse charge procedure).
You may still deduct the VAT you yourself have paid on your related expenses (goods/services bought in specifically to supply that service).
Now, your European billing address is located in Switzerland (Epic Games International S.Ă r.l., Baar Branch, Lindenstrasse 16, CH-6340 Baar, Swiss Tax Registration Number: CHE-358.969.724, EU-VAT Identification Number: EU528001425).
Although Switzerland is not a member of the European Union, it is a member of the Economic Free Trade Association (EFTA) and the signing of the Free Trade Agreement in 1972 formed the basis of economic relations between Switzerland and the European Union countries. Switzerland therefore largely complies with European VAT legislation, as defined under the Sixth VAT Directive (2006/112/EC). VAT-registered independent businesses operating from Switzerland will therefore be subject to the VAT directive, to the degree that the Swiss authorities are bound by it in putting in place standard and reduced rates within the permitted range, and setting the national rules regarding when and how VAT should be charged by registered businesses and individuals.
Under new rules coming into force with regard to the EU (and therefore having an impact on Switzerland, as described above) between 2010 and 2015, business to business (B2B) supplies of services will be subject to VAT in the country in which the consumer is located, rather than the supplier’s country of residence, with the business consumer required to account for VAT using the reverse charge mechanism (whereby they act as both the supplier and the consumer, charging themselves the VAT where appropriate, and then claiming it back). For telecoms, broadcasting and electronic services these changes are delayed until January 1, 2015.
Considering all the above, I think you should create a mechanism in the Account section for VAT registered members to enter their VAT number, and for those members Marketplace prices should be VAT exempt.