Ignoring the need for work on the boat which can extend the limit, the easiest solution to the 90 day rule
Buy the boat, re register as a Canadian vessel, sail to Bimini
, clear in, clear out and return to the USA as a Canadian vessel. You will be given a US cruising permit
valid for 12 months and you are now exempt from Florida
If you are anywhere other than Florida
when you buy the Customs
guys might know the law and actually give you the permit
without the vessel arriving from Foreign, that said you probably aren't due teh sales tax either!
We did exactly this, and agreed everything with the very helpful guy at the Florida revenue office in advance.
On where to buy, the advantage of USA is the sheer number of baots to choose from. Look at lots of boats there, then having decided what you want look if one is available for sale