Surely the best place to buy this is from your local motor factor.
Any decent sized trading estate worth its salt will have at least one.We have three and you can buy anything available at Halfrauds for considerably less.Have just paid under 9.00 pounds for 40AQD oil filter from a reputable manufacturer.
Said beforehand. Take the bit to the local truck factor. "One of these please" May be about 25% of the VP cost, +VAT. Get your oil there, get them to do injectors and pumps. All very competitive if you are prepared to do some DIY.
Volvo aren't too bad on filters, I've just bought 2 oil filters for my AD31's same as KAD42's etc.. I believe, they were only £6 each, secondary fuel filters were only £9 each all from a Volvo main dealer.