Hey Yank, I'm also looking for an alternative to the iOSD mini. My application however is a P1.1.1, so I must also consider the cost of the PMU. Together, they run $130, so I'm searching as well. I found two alternatives and both have LAT/LON co-ords. One is the N1 Naza at around $25. It has three switchable screens, one of which is very similar to the iOSD mini. The other is the S-OSD Remzibi, which is around $35. It is software driven for configuration and options settings.
The downside to each of these is little to NO installation instructions, plus there are some Chinese characters labeling the icons on the screen. In both devices, there is information online about what the Chinese means in English, but I'm not sure yet if it's worth the hassle.
I hope you can find something and if you do find more information on these two or others, please post, as I'll be watching this thread.