I'd go for an Astec alarm, designed and made in Ireland. The system features full tamper protection, digital voice dialler (no great difficulty in installing) and a choice of different options for sensors, light relay, smoke alarm integration etc. They don't need as much wiring as a more conventional system and I thought it was good value for money. I paid about €400 and got my brother (a sparks) to wire it, while I did all the builders work, (chasing, pulling cables, mounting alarm box, sensors etc). You can extend the system later if you wish.