I think that buying from Ebay can be fine.
But planning a long ride back on an unfamilar bike, especially one like an Enfield, which, while perfectly capable of long range travel, is not necessarily that well suited to it, is a gamble. Especially given the small dealer network.
When you buy a YamaHondaKawaSuki and it breaks down on the trip home, the chances are excellent that there is a dealer nearby. If you buy an Enfield, the chances are very good that the nearest dealer could be 100 miles away.
You are probably doing the right thing in buying from a local dealer where you can test ride first.