How to complete shell apartment to finished standard in Gozo?

Its difficult to say as there are so many different variables, and everyone has different tastes and standards. One can realistically spend anything between €18K-€40K,  excluding a Kitchen for say a 3-bed apartment.  Choice of apertures can also make a big difference (wood/aluminium, uPVC) and prices rise if apertures are arched.   Tiles and bathroom fittings  vary tremendously as you can buy tiles from €7 psqm - up to even €100 psqm.   A kitchen could be made and installed for as little as €4-6K, but realistically you should budget closer to the €10-15K mark including basic (as in not high end) appliances.  So there is no easy answer.  Hope this helps. It is best if you get some quotes for plastering, tiling, electrical and plumbing works, and then add on the cost of tiles and fittings, plus kitchen as these are very subjective.  Add on costs for air conditioners (prices vary between €650-€1100) per unit depending on unit size.