I own this system but the value of yours would really depend on the condition of the unit. if it was totally unmarked it's probably worth (on ebay) between £350 and £400 - you might get lucky and have two people in a bidding war that drives the price up.
The speakers value also depends on condition i.e no rips to fabric, RL straps still intact, does it come an optional floor/ceiling/wall stand etc.
as a rough guide i paid £350 for my mint condition BC 8500 (it came with all the manuals a pair of RL 1000's and a Beolink 1000) and i paid £50 for a pair of RL 45.2's with only the built in stand which were missing their straps but otherwise in excellent condition.I paid another £35 for a set of floor stands for them and £10 for replacement straps.