If you're Brazilian you already know this, but here goes ...
You probably won't find a decent bluewater boat in Brazil, and if you do it will cost the earth. I'm not sure I understand your intentions fully. Are you going to live aboard mainly in Brazil with the boat or France? You must know by now that a foreign flagged boat can't remain in Brazil for more than 6 months (or is it now a year the first time? I forget). This means that you're better off buying a Brazilian boat if you plan on spending most of your time in Brazil. The alternative is making bi-annual trips to Uruguay to re-enter the country again for 6 months. Depending on where you live this is a LONG trip and often in very dangerous waters, depending on the time of the year. From your name I take it you're in Ubatuba, right? Remember, you cannot register a used boat in Brazil (ie. change to a Brazilian flag). On the other hand, if you're going to spend most of your time outside Brazil- buy the boat in the US and NOT in Brazil. Boats are a rip-off in Brazil... The Real is strong and the US dollar is pretty weak at the moment. Boats will cost 1/3 of the price in the US (compared to Brazilian prices).
As far as what model to buy- everyone has their preference. There are tons to chose from. I do think you can buy a pretty terrific boat with your budget almost anywhere (except perhaps Brazil!). Outra coisa, as respostas aqui as vezes são meio grosseiras, mas as pessoas geralmente são legais.
As an aside, if anyone wants to sail their boat down to Brazil and sell it to me, just let me know! I haven't been able to find anything here I like! (I'm serious about this!!).