Don't buy a stone, buy a steel. They are usually round, weigh 8-10lbs. Treat them like cast iron but the hard oil coating (flax seed oil) wears off of a steel faster than cast iron, that's OK. I got one for about $15 at HomeGoods (Marshals sister store).
The steel won't absorb smells, won;t break (even the ceramic stones that won't absorb smells have reported breaking). Also, the weight, while taking much longer to get to heat, will help you make pizza after pizza because it retains the heat.
Tip: buy a infrared thermometer. Measure the steels surface right before placing on the pizza and note the temp along with a description of the coals and time to heat up. It will only take you about 3 pizzas until you mentally dial in the time to finish! I use my gun thermometer for everything from eggs, pancakes (never a first burnt pancake) etc.
Make neapolitan style for the easiest; very thin crust smaller pizzas that will finish in 5 minutes +/-. I never oil the crust; many people do but that's not necessary. The nice things about numerous small pizzas is you can make them all different.
My "oven" pizza stone is an 18 lb cast iron Grill and Griddle made for camping. That is far too heavy to get to temp on the grill.
Relax and practice; the mistakes taste good.