For a brand new, unused, unopened working Blackstar 500, $440 is a great price, If that price sticks.
As psuagro has mentioned though a few members have fried their BS500's recently. Of course if they had a warranty and sent it in they would have been fixed. Still, It is only a one year warranty so who knows if there will be problems after the warranties run out...?
Regardless of brand I would always go with two smaller units over one bigger unit just so if one needs to be repaired I'm not completely without light.
PS - The blackstars are fabulous for vegging. If anything they're a little "lightweight" for flowering.