Colin.
I take it you mean wheel arches similar to the Wide Track version of the Sportrak / Feroza
Are you sure they fit on the narrow track or do you need to drill holes in the existing guards ??
I know the wide track Feroza has a round wheel arch in the rear (a 36" tyre fits snugly into this space) I thought the narrow track didn't have a 'bolt-on' flared guard at the front or the rear.
It seems to me that £100+ (i take it that price is for one of them) or £400 seems like a lot of money which I'm sure could be better spent on other accessories for your Sportrak !
You should be able to easily fit 30" tyres without too much problems, 31" or 32" tyres with a body lift and suspension lift.
What are Irelands rules on tyres sticking outside of the guards ?? Do the Police 'crack down' on modified 4By's ????
If they do, then you should be able to get different flares (read cheaper) to cover the wheels outside the guards.
Anyway, if you have the money, spend it on a suspension upgrade and/or a body lift to fit the bigger tyres.
Cheers