I picked up the big brother of this Karcher for about £38 delivered a few months back. http://www.karcheroutlet.co.uk/products/product.asp?id=5072
They are a bit plasticy but they are great an no-nonsense. The filters are waterproof and they take bags or no bags. The bigger one I have is like the £99 one in screwfix but I have more parts with it (never seen so many) and it has the blow function which is fantastic for cleaning out the filter.
I’ve been using it on my flat while I refurb it so it’s been sucking up concrete, plaster, wood shavings, screws, wet filler etc etc. Only hiccup has been when I sucked up some large bits of wood that blocked the pipe but putting the hose on the back to blow it out fixed that.
But after all that I wouldn’t have one as my main home one as it’s not got a Hepa filter. For £20 that ^ would make a great garage/workshop vacuum and save you from ruining a decent one.
Take a look at Vax upright. We have a Vax one here for the pet hairs and while it has got a bit battered (clumsy housemate) it still works very well and keeps on sucking with minimal maintenance.