Looking at Lifeline fire - direct i've noticed the prices for the Zero360 have come down quite a lot since we bought our electric discharge 3kg thingy from Demon Tweeks. Last year it cost nearly £900 to have ours refilled and serviced, but that includes the explosive charge canister that provides the pressure. They do a 2.25kg hand held Zero360 extinguisher, but i'd still have a AFFF as backup to cool the area to prevent reignition.
I can get 2kg / litre AFFF with transport brakcet for £25 + VAT, I suppose if you ask your local fire extinguisher place i'm sure they are all about the same price. You might get discount if you buy a lot for other forumeers?
BTW, the Lifeline Zero2000 is very similar if not the same as AFFF
Also look on ebay for Halon / BCF extingusihers, they come up all the time.