Whittles Fabrics is carried Frolic fabric FQ bundles specifically for the Mystery Quilt.
https://www.whittlesfabrics.com/search/?q=Bonnie+hunter . Quilted Twins.com usually puts together bundles of MQ color fabric too, but so far I haven't seen it on their webpage.
Did Bonnie hint somewhere that thus will be an easier mystery? Maybe if I finish my Christmas quilts before Thanksgiving... I do love all things blue!