Sorry Bailey, I disagree - though ratboy does have a point. I have spent thousands each on domains that I probably would only have bought for £500-800 if they didn't have links, and I wish there were more domains out there that did.
When looking for domains with history I don't neccessarily need fantastic links from the BBC, even just a handful of directory links will do, provided they were got a year or more ago - the longer the better, frankly. It basically means that the domain that is sold with 'great potential' might actually manage to see some of that potential without having to hang around for a year or two before we get any traffic or revenue worth mentioning.
What I do take issue with is domains that have just been blasted with forum profiles or something similar, as often they will have a penalty that might take months to fix - apart from being bad seo its just lazy. An investment of £100-200 on some decent permanent links could multiply the value of your best domains. Obviously tho if the domain is only worth £50 to you the multiple is porbably a fair bit smaller - it may not be worth the time to bring it up to a higher standard unless you don't really value your time.