I always wind up buying ex commercial machines and then upgrading the hard drive to SSD and maxing out the ram.
It tends to be the most economical way to a machine with a decent case construction and processor spec, with lots of ram and a quick hard drive. Sadly that spec tends to shove you into the £1200 'ultrabook' market otherwise and £450 tends to put you at the top end of the home netbook market which means keyboards that feel like typing on a sponge, flexible screen casings, crap chassis and budget processors.
That said, dont do it if secondhand bothers you. I like it because I dont get precious about it if its already marked.