I purchased mine, which was exactly what your describing, an M30 Commercial, back in 2011 in the range of $1000-1250, but even at that time most similar guns were at the $1500-2000 range. So anywhere in that range would be about right.

I have seen relic conditions guns in the sub-$1000 territory but, when I say relic condition, I mean looked somewhere between a barn find and a battlefield dig up.

On other references, some matching broomhandles is excellent condition have enjoyed a huge price boom in Canadaicon staggering +$2500 but those are either antique large ring hammers, or other special cases.

My 50% value "guess" is based on the typical observed asking/sale prices of other pieces that have a Restricted counterpart, usually revolvers. A restricted "example" vintage S&W revolver might be $500-700 whereas a similar frame 12.6 revolver would be at the $250-350 price point. Beyond that it is a hard thing to really measure.

On a similar topic I have used this site as a great resource for history and identification, and to dispel some "facts" that I though I knew.

Mauser C-96