Below is the reply I received from WSEX. As you can see, it's less than a 10-cent line until -130, goes to 11-cent at -150, and 15-cent at -195. All considered, not bad, IMO. Draw your own conclusions.
Dear Customer,
Below you will see the money line conversion table with the
favourite and the take back. If you have further questions,
fee lfree to give us a call on our toll free
number,1-888-498-8227.
-500 440
-460 410
-440 390
-420 375
-400 360
-380 340
-360 325
-340 310
-320 290
-310 280
-300 275
-290 265
-280 255
-270 245
-260 240
-250 230
-240 220
-230 212
-220 204
-215 200
-210 195
-205 190
-200 185
-195 180
-190 176
-185 172
-180 167
-175 162
-170 158
-167 155
-163 151
-160 148
-157 146
-153 142
-150 139
-147 137
-143 133
-140 130
-137 127
-133 123
-130 120
-127 118
-123 114
-120 112
-117 109
-113 105
-110 103
-107 100
-104 -103
-103 -104