you could always go with a smaller low resolution display and attach a touchscreen to it for under $30 (that's what im doing right now)
Our SmartGPU has a high resolution LCD display with high brightness, however we think is not at 100% sunlight readable, it's about 80% sunlight readable.
However, the "SmartGPU" is a graphic chip processor, that it is connected to our LCD. So you can design with this processor by now, and later on just connect it to a sunlight readable LCD instead of ours, the Smart GPU is compatible with any 8/16 bit parallel LCD. We don't offer our SmartGPU board connected to a sunlight readable LCD because as you know, cost would increase a lot, and we want to keep it low cost.
Some people has bought the SmartGPU board to develop their application, and later on, they buy us just the Graphics processor chip and they connect it to their custom LCD(bigger size, Sunlight readable, different resolution, etc).
Actually what we sell it's the SmartGPU chip processor and it's technology, but to demostrate the performance and characteristics of it, we offer the SmartGPU development board connected to a normal TFT LCD.
Hope this can help you, feel free to ask us anything else!