The price of these Chinese heaters is very tempting.They are advertised from £100 to £150 so are very cheap.
A Propex gas warm air heater is around £500 and webasto and Eberspacher about double that.
While deciding on a permanent heating system,I am using a cartridge camping gas heater which works well,but in a small dog kennel cabin like mine the condensation it produces is dreadful.My boat has a mushroom vent,an opening skylight,a vent in the toilet box,a vent in the hatch,and the vent grill in the cabin door is about a quarter of it's size,and with every thing open the windows and ceiling are dripping .With all this ventilation it largely negates the heater,hence the need for something better.