Restoring aircraft is a brilliant hobby (or job) if you know what you’re doing.
Many people see aircraft going cheap on eBay and think this could be a great investment buy as the aeroplane may look OK and only need a bit done to it. Unless you are a registered aircraft engineer – DON’T BE TEMPTED!
If you intend for the aircraft to gain a new Certificate of Airworthiness then it could cost many thousands more than the cost of purchasing the aircraft as many parts of an airworthy aircraft are time limited and, unless the appropriate certificates for for those parts are present in the logbook, they will need replacing.
This is slightly different for home builds, but the regulations are strict for both.
In short – don’t do it unless you are an engineer (preferably a registered aircraft engineer) or are willing to spend a lot of money on work, parts and storage.
If you are serious about restoring aircraft then research it first. A good place to start is at your local airfield. If you haven’t already, join a club!