My advice would be to employ young architect, with ambition then I think you will get innovation at a reasonable price. If a larger practice is approached then they are likely to hand it to a junior member of staff. 300,000 to 400,000 is a decent budget and you should be able to get something good, indeed.
Architects in Scotland would charge about 10% for a full and complete service which would include development of design with the client, preparing working drawings and production information and keeping and eye of things on site as well as handling all planning and building control applications
You can charge per hour and I would sy about 60 to 80 euros per hour is a decent fee but would not advise that the house is undertaken in this way. If you want a design only or ideas then that would be reasonable.
If you get a good architect to design your house it will change your life...believe me.
Hope that helps.