Heather,
In Asturias you may except about 5 Euro per meter for internal walls, standard quality.
External walls depends on a lot of things… from a range of 6 to 8 Euro per m2 (paint only) it may change a lot if you need scaffolding (sometimes, depending of the house that may cost more that the painting itself) the kind of paint you may use, the type of anti-moisture or anti-dampness or even fungicides you may apply after the sealant and before the painting itself…
Cesar