128k for US<>Europe roundtrip in business is a very good price on DL, and one of the lowest you will find.
In very occasional instance, DL will have a "Flash Sale" or some other promotion where a lower price is possible, but 128k is the normal floor as far as anyone can tell.
This is actually one place where DL miles have not lost an immense amount of value. Back in the days of award charts (perhaps 5-6 years ago), the lowest US<>Europe business award was 125k RT. So a 3k increase over several years...not so bad in the grand scheme of things.