if CBG bought GBE, they'd have to buy the stock (as noted, maybe $40 million market cap) plus assume the debt of GBE. i doubt CBG's lenders would allow this to happen. paying out $40 million and adding debt is not what CBG needs right now.
i'm not totally in tune with these broker companies but i think these are more likely to merge/acquire during good times rather than bad times. in the past, i think several have gone private in bad times and then gone public again when times are good. i remember Eastdil (owned by wells fargo) bought Secured Capital a couple years ago during the go go days. and i think CBG bought Insignia sometime before that but not positive.