If thats a price for a new mk4 then thats OK, but if its 2nd hand then too much, they are between £350 and £450 for a mk4 on ebay, you *can* get cheaper units on ebay, I paid only £235 (inc del) for mine and took a chance.

BTW there are a few more differences between the mk3 and mk4, its a lot quicker for a start, its more configurable, you can read modded map discs to include speed cameras etc...

There is nothing wrong with the mk3, but the mk4 is just better.