Got one of these. Very powerful and does a great job. Bought mine in the last sale for £68, so its even cheaper now.
The kids have loads of fun with it - and the wife is delighted with her clean patio.
By the way, do not touch the other Challenge xtreme model (£39.99) as the lance will split after some use, and its practically impossible to find a replacement. Seems like they sorted that issue in this model.
Really there is nothing to lose at this price, considering Argos's return policies.
This is a really powerfull machine!
Was £89.99 a few days ago.