Show me a dealer who will pay 2/3 of retail price!!! PLEASE!!!! I've got a number of lenses I'd like to sell, but I found that most dealers were looking to pay 1/3 of retail.
To aware aware the OP is became necessary. The best way is to sell the lens is the APUG. Be an subscriber , took the lenses best pictures including showing the glass clear againts the white paper , add the serial numbers and most importantly tell the story where did you find the lenses from.
Below a classiieds ad for 425 dollars. If your lens is excellent , it makes more.

Leica 5cm F3.5 Elmar for LTM - Interesting Serial Number!
Leica 5cm F3.5 collapsible Elmar for LTM. The serial number is 595112, an early 1945 serial number possibly indicating this is "war-time" Leica. I had this lens CLA'ed recently (receipt included). There remains what is possibly (not sure) a very faint layer of haze and/or coating imperfection seen under very bright light, but the overall glass aspect is substantially clear and clean and I'm sure it would take pictures as-new. (My tech told me he did his best to clean this lens while not risking leaving internal scratches.) The iris is clean and the action smooth. The focus motion is smooth and precise. There are a smattering of micro-scratches and a bit of pitting on the barrel, all pretty normal for a 68 y/o Elmar, but overall this is a very decent lens. Sold as shown with original front cap in good shape which has a little sticker that says "Germany" on the inside surface.

Price: $425 plus insured shipping OBO