What were they asking for it? MR Clipart sell a great set for about $60 or €60 with just about all you need.
They do a package with a thick folder which I bought back in 93 for about $400, the cheaper version is just the CD and a pdf file with all the vehicles, or you can do a subscription with them for about €100 or $100 for the CD and a year of downloading or requesting images from their site at no extra cost, they are, have a pretty extensive range and will try and digitise stuff on request. you can check them out at http://www.mr-clipart.com
You also have Impact Sign Services, Brian Hayes in the UK, we have their CD too and feel that those 2 products pretty much cover all you need…no collection is perfect.