This Technical Bulletin from Practical Action gives details on drying, milling and packaging chillies.
The bulletin gives information on both solar drying which works well in dry weather and other dryers than can be used when the humidity is higher.
The article can be viewed in text format online and can be downloaded as a pdf document with pictures. To download one needs to register, but their is no charge.
The article includes the contact details of two dryer suppliers, but they are both in India. This is an issue I think we could try and address – the supply of up to date and more comprehensive lists of suppliers.