On ebay 120721841438 is stainless at about £8.69 delivered.

For plaster I would stick to stainless tools, inner & outer & float
trowels. It does not cost much more for stainless.

The cheap trowels are ok, they do distort into a bowl, will ripple if
provoked and do not like any miss-handling. They are ok for DIY use -
ie, do not expect to be using them commercially day in & day out.