There have been about two dozen threads on this same subject in the last two years.
In addition to the boats you've named, I'd also add the Southern Cross series of boats, by CE Ryder in Rhode Island. The major caveat with them is that they had a cored hull—which used AIREX foam as a core material. However, the boats are very robust and seaworthy. Donna Lange recently completed a circumnavigation in her SC 28.
The Pearson Triton, Bristol Channel Cutter, Flicka, Pacific Seacraft Dana 24, and Contessa 26 are also boats that have done similar passages. However, I seriously doubt you'll be able to find any but the Triton in your price range.
Be aware that using biodiesel in a marine engine may not be such a good idea. It has some properties that are going to cause problems for an older boat, which was not designed to use biodiesel specifically. See quoted text below.
I would also highly recommend that you reserve about 15-20% of your purchase budget for refitting, upgrading and repairing any boat you buy. This is especially true of a boat you want to take off-shore for any extended period of time.
Finally, you're not generally going to find a seaworthy boat in your price range that would be liveable for anything but the shortest of time periods with more than two people aboard. Most boats can sail with far more people than can liveaboard them. My friend describes his C&C 38, a much bigger boat than you're looking at or able to afford, as "Sails 6, Feeds 4, Sleeps 2".
I'd recommend you look at John Vigor's book, 20 Small Sailboats to Take You Anywhere. Some of the boats in that book are inherently more seaworthy than others...and some I would hesitate to recommend for making a bluewater passage without serious modifications.
Pure biodiesel (B100) has a solvent effect, which may well release deposits accumulated on tank walls and in pipes from operation. It will also attack paint and similar surfaces, given the chance. Using high blends of biodiesel, the release of deposits may clog filters initially and care should be taken to replace fuel filters until the build-up of deposits is eliminated. This issue is less of a problem with B20 blends, and there is no evidence that lower-blend levels such as B2 have caused filters to become blocked.
B20 and B2 refer to the American system of designating the percentage of biodiesel in a blend. B20 contains 20 % biodiesel and B2 contains 2 % biodiesel by volume. The rest will consist of standard fossil diesel fuel.
The recent switch to low-sulphur diesel fuel has caused most OEMs to switch to components that are also suitable for use with biodiesel. In general, biodiesel used in pure form can soften and degrade certain types of elastomers and natural rubber compounds relatively quickly. These were commonly used in engines up to a few years ago, so there may be a compatibility issue with older vehicles. Using high percentage blends can impact fuel system components (primarily fuel hoses and fuel pump seals) that contain elastomer compounds incompatible with biodiesel, although the effect is lessened as the biodiesel blend level is decreased. Experience has shown that no changes to gaskets or hoses are necessary when using B20, even in older engines.
The final issue to be covered is that of shelf life. Most fuel today is used up long before six months, and many petroleum companies do not recommend storing hydrocarbon diesel for more than ix months. The current industry recommendation is that biodiesel be used within six months, or reanalysed after six months to ensure the fuel meets ASTM specifications (D-6751).