Those seem like good prices for those 2 girls as long as they are quality animals, which it sounds like they are.
And you may be able to get alittle more knocked off in a package deal since it wouldn't cost anymore to ship both of them compared to just one of them.
As far as not finding anything on the BOI, don't necessarily take that as a bad sign. People don't always remember to post Good Guy threads when the have a successful and enjoyable transaction, but will almost always post about a transaction that has gone south. I will be the first to admit that I haven't created a new thread for every positive transaction I have had.
That being said, definitely take Daybreakers advice and post an inquiry thread to attempt to get more information about the seller. And even if you don't get much of a response go by your feelings. It sounds like so far it has been a good experience for you and if it continues to do so I wouldn't hesitate to do business with someone based solely on the fact that there is nothing on the BOI.