SPUDZ,
Is it a timber stud wall or solid wall? Knock on it to tell the difference, stud will be hollow sounding, block will hurt your hand.
Considering, steel, supports, skip, doorframe, plasterboard, plastering, architrave & skirting you could start about €1200 and end up around €2000 depending on location, access, protection of existing, wall structure, load etc.
You would also need to consider inclusion of an engineer to sign off on the steel details to ensure your alterations are compliant & structurally sound, allow €250 - €500 for this, again factors of complexity, site visits, certification all play a part in this cost but this is critical should you wish to sell the property in the future.
Sean