You'll need to disassemble to verify fully matching but if that's the case then don't disagree with everyone's estimate. Holster is an Audley which is collectible in its own right. Simpson has a nice one for sale @ $600 to give you an idea of what these can fetch. Please let us know what you decide to do. Looks to be a nice, solid example.
If it’s all matching to me I would certainly consider it a ‘collectible’. WWI Luger over 100 yrs old with original finish and matching numbers may not be considered rare, but they aren’t cheap or exceptionally easy to find either. Only WWI Lugers I’ve personally wanted to take to the range are mismatched and/or refinished. Just my opinion but if it were me I probably wouldn’t risk shooting a nice matching example especially if it was a family piece that had some type of significance. If matching agree with the estimates already provided, maybe 1200-1500