I think Don Classics, Sound Skultor, AML, Golden Age Premium etc etc really have the quality vs price bracket nailed. Any cheaper in and you are in Alctron and Behringer territory, which I think is too low grade component wise.

A less obvious bargain would be a used Louder than Liftofff Silver Bullet MK1, because its a stereo pair of Neve AND a stereo pair of API, plus you can use it as a fantastic saturator