David,
I bought my 1st M-3000 Mauser in 1975 for the princely sum of $225.00. I sold it about 10 years later for more than double that. More recently, (in the last 5 yrs) I have bought another .243 Win, a .308, and a .270. I paid $350-$500 for each of them. And I'd buy another 1 or 2 if the opportunity should arise.
Being you mentioned M-3000L, I am assuming the left-hand version. I would expect the left hand to bring a bit more. Just guessing here, but I'd think a bare action would bring $350 + and a complete rifle, likely $500-$600. But it's very hard to say, as not enough of them get sold to establish a hard line price.
Sorry, that's the best I can do...
GH