I have a Sirio S21 S. It is a 3 port and it is really solid. Most major engine companies have a 3 port for around $200. Your best deals are on eBay. The Go engines are $200 for the 7 port motors and have heard good things about the "NEW" model. I would never buy a used motor!!!!!!!! Get something you can afford off of eBay new.
I also have a hyper 8 port in my sons Hyper 8 and it is wicked fast. I have it running rich just so the kid can control it. They aren't as high of a quality but they are ok. A little tough to tune when they are well used. James