Hi Timothy,
According to the web page for Seydel harmonicas, they build and sell the lowest Richter-tuned diatonic harmonica in the world: the model 1847 LLE (which stands for Low Low E) is relatively new in their product list and seems to sell for around 107 (US ) for the Classic model, and about $130 for the Noble model.
They also offer the Classic model as a high Bb also for about $107. I have not looked into such high ranges so I do not know if anyone offers higher range harps that are still of good quality.
Seydel 1847 model harmonicas are exceptionally good and have stainless steel reeds. Their models with brass reeds are priced more like Hohner and Lee Oskar harmonicas. I own and play both the Seydel 1847 models and their less expensive brass reed models as well. All are very good harps – as are the Hohner Special 20, Marine Band Deluxe and Rocket models (which I also own and play).
Regards,
– Slim