You can buy the speakers on Amazon.com for about $80 USD new per pair
Find the amp on Ebay for much less than retail,
As for the lids, I've seen them and they are nice however you could
have a local auto body shop cut in holes for the 6x9 speakers and you
can mount them with the grills on top, painted to match the bags.
I haven't found any discounts on the Yaffe/Cycle Visions bags, however I
did see several people mounting speakers directly into the bags as said
above and it looks good...
"My rule of life prescribed as an absolutely sacred rite smoking cigars and also the drinking of alcohol before, after and if need be during all meals and in the intervals between them." Winston Churchill