Have a look at Kappa Moto.
Made in the same factory as the Givi and comes out a lot cheaper.
I have 2 sets of Kappa panniers, a set of K21's (same as Givi E21) and a pair of K960's and a set of Givi E36's that all fit the same racks on our bikes.
The Kappa K40 panniers come with an attractive price tag and are well put together.
Have a trawl of Ebay, but check the Italian listings as I bought a Givi V47 topbox for £125 delivered where the cheapest I could find in the UK was £175.
Kappa also do a range called Garda which is the nice looking Givi trekker boxes with a different logo on them. (33 or 44 ltr available.)
all depends what you want to spend and how big you want them.
