Masha,
In your search for a used one you can extend to many more models on ebay as it's a fairly common part across the range
http://www.realoem.com/bmw/partxref.do?part=13631461852
"
Part Cross-reference
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Part 13631461852 (Switch) was found on the following vehicles:
259E: Details on 259E
259E R 1100 GS 94 (0404,0409) N/A, Europe
259E R 850 GS 95 (0403) N/A, Europe
259R: Details on 259R
259R R 1100 R 94 (0402,0407) N/A, Europe
259R R 850 R 94 (0401,0406) N/A, Europe
259S: Details on 259S
259S R 1100 RS 93 (0411,0416) N/A, Europe
259S R 1100 S 98 (0422,0432) N/A, Europe
259T: Details on 259T
259T R 1100 RT 96 (0413,0418) N/A, Europe
259T R 850 RT 96 (0412) N/A, Europe
59C1: Details on 59C1
59C1 R 1200 C 03 (0329,0379) N/A, Europe
59C1 R 1200 C 97 (0424,0434) N/A, Europe
59C1 R 850 C 99 (0421) N/A, Europe
59C2: Details on 59C2
59C2 R 1200 Montauk 03 (0309,0319) N/A, Europe
59C3: Details on 59C3
59C3 R 1200 C Indep. 00 (0405,0433) N/A, Europe
59C3 R 1200 C Indep. 03 (0362,0391) N/A, Europe
89V1: Details on 89V1
89V1 K 1 (0525,0535) N/A, Europe
89V1 K 100 RS (0523,0533) N/A, Europe
89V2: Details on 89V2
89V2 K 1100 LT (0526, 0536) N/A, Europe
89V2 K 1100 RS (0522,0532) N/A, Europe
89V3: Details on 89V3
89V3 K 1200 LT 04 (0549,0559) N/A, Europe
89V3 K 1200 LT 99 (0545,0555) N/A, Europe
89V3 K 1200 RS 97 (0544,0554) N/A, Europe
A61: Details on A61
A61 A61 (9251) N/A, Europe
K30: Details on K30
K30 R 1200 CL (0442,0496) N/A, Europe
K41: Details on K41
K41 K 1200 GT 01 (0548,0558) N/A, Europe
K41 K 1200 RS 01 (0547,0557) N/A, Europe
R21: Details on R21
R21 R 1150 GS 00 (0415,0495) N/A, Europe
R21A: Details on R21A
R21A R 1150 Adventure 01(0441,0492) N/A, Europe
R22: Details on R22
R22 R 1150 RS 01 (0447,0498) N/A, Europe
R22 R 1150 RT 00 (0419,0499) N/A, Europe
R22 R 850 RT 02 (0417) N/A, Europe
R28: Details on R28
R28 R 1150 R 01 (0429,0439) N/A, Europe
R28 R 1150 R Rockster (0308,0318) N/A, Europe
R28 R 850 R 02 (0428) N/A, Europe