I recently visited Home Depot and they had a clearance on a two piece adjustable cooking grate in their BBQ section. Originally these were just under $10. The grates were on sale for about $2.50. One section is about 6 inches by 10 inches. The other is about 6 inches by 12 ½ inches. I bought two sets. I wanted 2 of the short sections so that I could fit them inside the foil trays I found. This would allow fairly flat storage when not in use. The two grates overlap each other to form the larger cooking surface.
I also found a multi-pack of foil drip pans in the same section of Home Depot. These worked out to be about $1 each. These foil pans are 12X8X2 . I am sure you could find cheaper ones, and of a size to also use the longer section of the cooking grates.
So with tax each portable BBQ grill is under $4 including tax.
One layer of hot charcoal briquettes will do 2 to 4 hamburgers or 2 good sized steaks. It’s a perfect size for two people. I tested this out last night with 2 steaks. I forgot how much better a grilled steak tastes done over charcoal.