If you are going to buy a boat for long term cruising, can I suggest a flight to BVI, you will be blown away, not only the price but the amount of boats you can buy, well worth purchasing boat overseas if you are planning on sail around world anyway.
Don't be put off buying a plastic fantasic as hundreds of them sail around the world each year and a cat is fine, I would still buy a mono due to cost. But do avoid slow old full keel design boats, they belong in the past, leave them there.
Good luck