Inexpensive battery smoke alarms

[eamonn123456]

I am looking to buy about 8 standard (ionisation) battery powered smoke alarms. Would like to get reasonably small discreet ones.

Anyone know where is the cheapest place to buy these, either online or offline please?

 

[landlord]

B and Q buy 2 get one free offer. The two will cost you I think about 12 euro.