A Metrol is probably going to be your best bet as far as price/quality and ease of instillation. They are a big OEM supplier in Japan for limit switches, workpiece switches, and tool setters and they recently (2015) got into the spindle probe business. It's a 2.4ghz system with it's own receiver included in the kit. It's on accuracy/speed par with Renishaw, but not super fast like the Blum. It is, however, significantly less expensive than any other quality spindle probe out there ~$5000 on the list price for the whole kit.
It is also Yamazen's default for new Brother purchases. They are the US importer and they have all the necessary documentation to get one wired into a Brother with relative ease (including their own custom macros and manuals). I am sure if you buy from them, they will be happy to walk you through getting it installed on a Brother.