Hi Sergey,
I bought this one from Maplins. There is a 10Watt one too but I thought maybe that's overkill. The 7watt one is big and solid looking.
Another tip, the tin? wires on the resistor are soft, flatten the ends with some flat pliers and then you have bayonets to plug straight into the plug. The round wires dont plug in as nicely.
http://www.maplin.co.uk/p/wirewound-...resistor-l470r