I would expect to pay $1500 to $2000 for a luger of this type with one matching mag, and a holster/tool.
The big online retailers would try to sell it for more, like $2500 =/-.
Police lugers are not the most popular versions of this classic pistol; but they do seem to be gaining a little more respect(and pricing) these days.
Having a commercial holster is a bit odd, as most police "rigs" have government contractor marked issue holsters.
I'm not convinced the hand written number inside is a "police" number- but it makes little or no difference to the value or desirability of your rig; if it were the same number as the pistol it would be an enhancement. JMHO.