As far as for the parts you will basically need you are correct. Or at least to get you started anyway. As far as what you will end up spending, I think for twins you will be over your initial budget hopes if you do it right and are using used parts that are in nice shape.. But you never know..
The boat will be better with the bravos, it will also be more reliable drive wise which will also make it worth a little more. It will certainly help you handle a little more power with in reason without adding much drag. I would not look for a bravo 2 or 3 for your hull as it wont benefit you speed wise or durability wise. But both can bolt to the standard b1 gimble housing..
I usually never have any used or take out stuff to offer, but currently I do have some used take out bravo stuff if it interests you.. I can also get you new components if you need them.. You can reach me during the week if you need any of it.. Jamie / Lakeside Restorations 570-639-2628