It seems that the current "brand new" price for one from Albion is $880 (
http://www.albion-swords.com/swords/albion/nextgen/sword-medieval-talhoffer-xva.htm) and Google suggests that currently that is worth around £634.
Second-hand and lightly-used is probably worth a bit of a reduction in price, but if it's still in "like new" condition, then probably not much of a discount.
Some people buy their Albions for the investment; others for using it. Depending what the other person is looking to get out of the deal, and how satisfied he has been until now with having that sword, the price will be different. if he feels he has received his money's worth by having it on the wall, you can negotiate a lower price. If he feels that it was a wasted investment, or indeed if he feels that it was supposed to have been an investment for the future, then the price is likely to be higher.