Space scenery is easy as. For astroids you can checkout the pebble section at the local garden centre. (or one of the councils heaps of roading material, but I didn't say that) You don't even have to use stone, just spray some garden bark chips black, and give them some grey dry brushing. As for planets you can get a polystyrene ball, and give it a coat of whatever colour you want you planet to be. Or you can buy a cheap globe, and cut it in half. As long as you don't mind fighting around earth all the time, lots of battles of the line, and fighting off the drak.