That deal seems reasonable, but at this point, the B2RE is an old design and it wasn't exactly cutting edge when it was new. There are plenty of newer amps that have more impressive specs for the money.
Regarding 8 Ohms or 4 Ohms, I personally don't think it will make a big difference. With two 8 Ohm cabinets, it's still a B2RE pushing at best 450W - this is not a lot of power by today's standards. So no matter what you do, it's not going to overwhelm two guitarists and a drummer. I would find a cabinet that sounds great and buy it without even thinking about 4 or 8 Ohms.
The -only- exception to that advice would be if you KNOW you are going to run two cabinets in the future. In that case, find an 8 Ohm cab.
If you're cool with all of this, a B2RE and a 410 is a great start. It's the no frills, all business entry into serious gigging equipment. I would try to work on that price, though. Good luck.