As always it is easy to buy a dog and most of them fall into this catorgory , there are a few very nice examples but they are all in the hands of people who have spent a lot of money to maintain them and so it is unlikely that you would get your hands on one of these.
My advice to you is to look for a structualy sound dog !. Idealy the engines will be just approaching overhaul and the paint , avionics , interior and de-ice boots will all be very well worn.
The buget will look a little like this:-
Engine/prop overhaul £ 35,000.
Paint / de-ice boots £ 15,000.
Avionics £ 35, 000 ( GPS ,8.33 DME , ADF , HSI/RMI )
Interior trim £ 8,000.
Nif-naf & trivia £ 5,000.
As you can see not cheap but it will leave you with an aircraft that will give years of good service , perhaps this is why old twins can be had for what look like bargin prices !.