Hi,
I can build a working model of this app within 12 days or less for 450 Euros and the finished product withing 2 weeks or less. The user registration and login part is a cinche.
What kinds of projects would the users be able to create? It would be good if we could talk on the phone at some point to get a better understanding of you are looking for in the final product. I see that you are in Denmark. I am in Chicago, so 7 hours behind you. Are you available after 16:00, your time, tomorrow? I find it a lot easier to communicate expectations through the phone.
I look forward to hearing from you!
Thank you and regards,
- Nicholas