The Metabo is only 900m3/h flow (on a 550W motor), make sure that's enough for your requirements. A lot of power tools that run on 100mm duct will general need more than that.
I bought one of the Axminster hobby units and used the blower unit on a homemade cyclone using a metal drum that I got off a farmer for a tenner. The unit I got was around £220 last year (probably more now with Axi's recent ridiculous price hikes) but has 2000m3/h on a 1.5kw motor. Bit of extra work but worth it for the better results. That said, you do could still do that with a smaller volume unit.
Also be aware that Machinemart stock the Metabo at £190 but are running their usual January Vat/10% sale on specific days. If you have a Machinemart near you and they give you the discount (often needs an invite if you are on their mailing list) that will drop the Metabo to £172 -ish and you can collect reducing any delivery costs.
Another option would be to wait for Ebay auctions, that way you may pick up some extra ducting as well as part of the sale.
