Motobins in the UK www.motobins.co.uk
sells a replacement for the Brembo calipers that is manufactured under the GRIMECA brand at £85 each, approx. $140 (Capital Cycle also offer the part at $220 each). Rebuilding yours with an overhaul kit, $20 from various sources, including Capital Cycle www.capitalcycle.com
, is something to consider if the caliper is basically sound.
Current - '74 TR5T : '93 R100R : '06 ST3s
Past - Variety of British, French, Italian, Czechoslovakian, and German bikes from the '70s, '80s and '90s