Just picked up an A1 condition Lenovo T430 (i5-3220M, 4GB RAM) for just £100 using that popular boot sale app. It was listed for a bit more - I've bought it for a relative but quite honestly I'm tempted to keep it.
Business grade laptops like this are generally upgradable (should be fairly easy to switch out the hard disk for an SSD and add an extra 4GB RAM, watching youtube videos if uninitiated) and sturdily built.
Obviously go and see it first, ensure that the charger plugs in securely, hinges are well seated, case is uncracked etc. before handing over any cash.