Bosc Monitor Substrate??

im keeping my bosc monitor on soil now, but weve found out that the soils infected with some sort of bug. So im taking all the soil out and throwing it away, and disinfecting the vivaium. I'm thinking of changing the substrate from soil to sand. The sand at reptile shops is expensive though, so im thinking of using childrens play sand? Is that okay?? And the reason i dont want to use soil is because those bugs always seem to spread in it. So im trying sand. Also should i disinfect the rocks and logs that are inside his viv too. Thanks