I found an umlaufbahn the black galaxy one for 450£ last year.
Other under the radar frames to consider imo: trek t1 (one 55 sold on Ebay for under 300£) the elusive esaki of course, the curvy top tube black/white or red langster, all of which could build fast and agressive
Don’t worry I didn’t for a second it was suitable, but stranger things happen.