Complete, or just the mechanism? It's good that you found one. Is that a usual sort of price for one in the UK? Add internal postage, of course, which should not be too much, and that makes a sizeable cost.

The last couple that I bought, in 2004 and 2005, cost USD18.99 (AUD27.40 at the time) and AUD32, delivered.
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(60x) 13DT + 3PB + PTPro; (G3) 7DT/MT; (G4) 3T + PB. System 8.1 to OS 10.5.8