I am trying to sell and Alexander 200 model french horn. It is rose brass and essentially brand new. Anybody know what a reasonable price to sell it for would be? Thanks!

Brand new the 200 series goes for about $8,800.00 (list).If you can avoid the retail market somehow you might be able to purchase a new one for $6,000.00.

Used 200's in primo condition go for about $8,000.00.
Deduct accordingly for lack of maintenance, dings, blemishes, etc. (Maintenance: if you don't oil the horn everytime you get it out, every hour of playing, and when you put it away then it is lacking proper maintenance).