Boge shocks are standard equipment, If they are Blue or purpley/red then they're "sport" shock, black is standard spec.
Ventura springs are cheap and cheerful, They used to come with the Bilstein Streetline kits which are their entry level lowering kits, how they actually respond on an A4 i've no idea, and i guess how much you've been offered them for comes into play here.
I would try to go for the "sport" spec dampers if you can. 40mm is a respectable drop, although this is measured from standard ride height, so if your car is a sport it will only lower it about 20mm or so. Imo is about the best ride height for an A4 without it being too low and ruining the handling and having no compliance while still looking good