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Trade Shows and liquidation sales are a great place to get ideas as well as establish relationships with wholesalers.
Outside of the UK, China is the cheapest place to find wholesale stock.
As far as drop-shipping concerned, it is often cheaper to take care of shipping yourself when you first start out - if at all possible! It's more work, but it gives you a little bit more breathing room as far as profit margins are concerned. Aim to build up to drop shipping when you become more established.
Finding a product to sell takes time and most people try several different items before they find a niche.
If you are on a budget, or lacking space, consider researching small products that are easy to store and cheap to ship, e.g. music, golf balls, ties etc.
Hope this is of some help and good luck!