Sorry but I don't buy it. I don't "begrudge" your bonuses - where did you get that from? I don't live in AZ (or the States for that matter) so I don't know how far away towns are from one another. I live in the Great White North, where we have 1/10 of your population on 10 times the land. Around here, past the suburbs, to get to far away towns is usually a long, lonely highway drive. In the city and the 'burbs, I have to deal with parking meters, traffic, crappy roads that damage my van and incredibly high gas prices (usually over $5/G). To say you have to work harder than someone else is simply not true. You may have to drive further but that's about it - the work itself is the same. I'm pretty sure that a highway drive is much more relaxing than city traffic. Also, although I know some shoppers do assignments on their way home from their day job, for me, this is my day job. I shop full-time. A company that takes away $16 per shop when I was doing 6-8 of these per month puts a serious dent on my bottom line. Do you honestly believe that a shopper in a remote location is getting that money? I know for a fact that they're not because the shops are listed on a board and they're all listed at the same fee.
Anyhow, my point was not this generic "some company paid me bonus money for going to such-and-such town". It was specifically about SI/IT. They're stingy with bonuses and that's a fact.
As for your 12-hour day, there's no way in hell I would have done it for so little. Only you can determine your worth. I charge a set fee per km so in your case, 425 mi is 684 km. I would have charged $383 in gas expenses on top of the regular shop fees.