David Kilpatrick imports instruments from Eastern Europe at very reasonable prices. http://www.troubadour.uk.com/ is his site, and he's a Catter too. Seems like he's maybe not still going on the importing though, but you could give him a call.

If you want volume to cut through, you're probably looking at an F or A style mando instead of the flat Celtic one.

You could also consider an octave mandola (octave down from a regular mandolin) if you want something more in the guitar pitch range, but they don't really have the punch to cut through a roomful of guitars. Usually I use a 1mm pick which gives nice tone - I keep a 3mm pick for when I need volume and sod the quality! :-)

Graham.