Well you don't answer the operating system question.
The site you give seems to be $200 plus postage and up for each module ,more when you put it all together and you have to be a ham already to make it sensible.
I repeat , there is little to no support for Linux that I have found .
The modules needed are expensive but there is no monthly fee.
What I am looking at is an arduino board and chip $8 , an ethernet shield $20 , a USB to ethernet server at $39 atm and a monthly rental of $15 for the USB 3G modem to send to my mobile phone. So $70 all up electronics or cheaper for each node plus a monthly rental to send an sms or email to my phone anytime.
Now GPS is a different matter and requires another shield
I certainly would like to now more about ARPS if you will give it . Especially current programs that you run so I can understand this better