Depends on what you're after. These 'hose lances' rely on water pressure to produce the foam, and to be honest, unless you have Niagara Falls as your water supply, the presure's gonna be crap.
Honestly, if you're prepared to spend £60 on something like that, you can buy cheap karcher pressure washers for around £70-80. I bought an el-cheapo karcher foam attachment for around £15.