Hi,
My name is Yury, I'm from Russia. Sorry for my poor English.

I've made the similar project, but with difference, at first my stations are fully wireless, it meant it dosn't require PC, Internet, even AC power. It use solar cell for charging Li+ batt and GPRS for uploading data on MySQL base.
Additionally it logs temperature, humidity, air pressure and calculates dew point.
Currently only one station is works, you may find it here:
http://pripyachka.com/g.php?info&n=4 in charts and here:
http://pripyachka.com/t.php?info&n=4 in text
it's located near my home (~15 km to south from Moscow, a half way to DME airport)
Sorry, only in Russian is available right now.

Another two stations was located in Pripyat town (near Chernobyl NPP) in Ukraine, it's N6 and N10 (also N5 before), you may change last digit in website address to change station No. But it was stolen by marauders.

Each station contains 3 parts:
1) the base
2) weather sensor
3) security sensor

each part is wireless, contains RFM22 868MHz module
Weather sensor has BMP085 sensor for air pressure and SHT21 sensor for temperature and humidity, sends data every 15 min. It use LiFePo battery for power, one charge it's enough (I believe) for 2-3 years
Security sensor has photodiode, amp, mcu (mega88) and RFM22. Only the light hits the sensor, it starts to tranmit data within 6 min and base station listening for the data every 5 min. In alarm case base station will send SMS to my phone.
Base has SIM300DZ GRPS module (new one use SIM900D), RFM22, ATmega644P, HV source for GM and big one GM SI22G (СИ22Г). Battery is Li+ 18650 5p1s (one model has 24p1s, no need to charge it up to 20 months). It turns on receiver every 5 min for one sec, and every 1 hour it uploads the data to website. Right before uploading it turns on HV and counts radiation within 10 min.

I have plans to install the same stations in Pripyat, Chernobyl, Kiev, Minsk and a few in Moscow region and so.
More information you may find here: http://forum.pripyat.com/showthread.php?t=5217

Thanks, Yury

Krzysztof,
At first, thanks for the warm welcome!

Ok, one station w/o weather sensor (only temperature and radiation) it cost around $45 excluding PCB and GM. PCB is ~$25 for manufactory setup and ~$2 for 1 pc. I have about 50 pcs of SI22G GMs, so I don't care about its cost.
http://www.ebay.com/sch/i.html?_nkw=si22g around $20

Actually, it doesn't matter what type of counter to be used.

Weather sensor's cost is about $50 and in case of use this sensor you need to assembly transceiver to the base, it cost around $9

Additionally you need to pay for GPRS traffic. But in Russia I use "Beeline" mobile network with a special tariff, in case of one batch of data is smaller, than 1kB, it will free of charge. So, it works already 4 month for free :)

No problem, I can release diagrams and firmware (maybe 2-3 days later, now I'm still in Kiev).
I would like to share results, but I've no idea how to do it? I'm not good in PC programming, I find it easier to upload data to a database by using a HW device, than using PC :)
BTW, in last FW version there's possibility to update FW through website (use Atmel dataflash chip for buffer)

Thanks,
Yury.