Make sure you have a full history with it & if poss,find out if it`s had a new alternator.If you can also find out weather the pollen filter has been changed regularly & if the brake discs & pads have been done (indicates hard use ).Also check for tyre wear.Listen out for beeps ( ie same as door open when your driving) this could mean the alt is on it`s way out.Make sure all the electrics work but do,do be particular about the electric parking brake PLEASE!!!
If its a good drive ( it should be) & the money is great then it`s up to you.
I have a 53 plate 2004 2.0 TDCI Zetec,I`ve had it 20 months & ok I had to change the alt,but apart from that it`s been fab.
Best of luck