The majority of the cheap one's for sale are the 2.2 Direct engine which was on BBC watchdogs programme as nearly all of them have had to have fuel pump regulators replaced I've even heard of them going 3 times in 1 year and at around £500 a time to get replaced u wonder why people sell that model for cheap?
If u have around 3-3.5k go and look for and test drive a mk3 Mondeo Titanium x or even better the ST220 with leather recaro's u will soon realise how crap Vectra's are in comparison.
It's the 1.8 VVT engines that seem most common
I've scoured Auto Trader for the past hour and haven't found a nice example Mondeo Titanium X for ~£3k