Cheap GSM dialler

I'm an elderly farmer. Nearly everyone round here has had their quad bike stolen.
I want to make a dialler from an old phone with a couple of solenoids to press the
buttons so it will speed dial.I wouldn't confront any theif because a neighbour ended
up hospitalised when a gate he was trying to detain them with was rammed.
There are sim900 sheilds but they seem rare and fairly expensive.
I'd love to hear from anyone with any ideas. Thanks John.

How about a device like


Mini-GSM-Tracker-GPS-Anti-theft-Realtime-Remote € 15,14 free shipping to Germany.

Is that cheap enough?

Hi, the theives are pretty wise. The battery angle grinder makes light work of locks and chains!!!
What I want is a covert pressure pad under a wheel which will dial my phone and I can see what's
going on via the cameras. I fancy a bit of a project.

I bought a itead 5216a 3G for $65, but I haven't been able to get it to work.
I am very new at Arduino, so it's probably on my end.

Well I made it!