I've been working with OpenGTS since 2007 and have written DCS software for many different devices
To get started, and to provide a more competitive price I will need the GPRS communication specs of the device, if it is the TK103, as I suspect it is I can certainly come down to about $200 USD, I only need to verify that it is the TK103
You will also need a device online for development and testing of the the code. Sounds like a long time, but 14 days would be about the correct amount if time to make sure all is working properly, agree?
By the way, there is no PHP code in OpenGTS it is written in Java, I am the real deal when it comes to OpenGTS and GTS Enterprise, and talk to the author Martin several times a month