Dealers sell this one for around £250-£300 depending on condition, private anywhere between £150 and £250, plus there's one on Ebay just now I think, so you might use that as a guide. There's been a couple of late on there, so it might be that's picking up people's attention. Not a huge number, maybe only three or four, but there is a certain cache with the Meridian name, high end appeal kind of thing.
Best place to sell is open to debate. Ebay gets you the biggest market, but high fees for both it and PayPal. Hi Fi Adverts, Gumtree and Hi Fi World, also Hi Fi ** are also free, but limited audience to some degree with those. Expect to hand over circa 10% fees for Ebay/Paypal.