A well-prepared action can be worthwhile; the cost consequences should be calculated.
Where the other side is solvent and the evidence is sound, an action may be the right path. Under section 41 ZPO the losing party reimburses the winning party’s procedural costs. If you only partly succeed, however, costs may be set off or apportioned under section 43 ZPO, so that you bear part of the costs yourself.
Before bringing an action, have the amount in dispute, the prospects of success and the expected expert costs assessed realistically. This avoids the procedural costs consuming the economic benefit.