In my home studio (where Alio and I record 'Sounds of Folk' for Radio Britfolk - shameless plug!), I came up with a great flash of perspiration...

I bought some cheap 'sapele print' internal doors, and stapled some contract carpet to them. Fastened to the walls and suspended from the ceiling they serve both to 'dry' the acoustics of the room, and to inhibit external noise.

The doors only cost six quid each (roughly 11 US dollars), and the foam-backed contract carpet was being binned by one of our suppliers at work after a stage show. They were delighted when I offered to relieve them of the responsibility of dumping it! Such a shame - it had only been used once, yet they couldn't use it again...