Someone mentioned a grill basket set from Costco. I looked online and saw a set of two grill baskets on sale at Costco's website for $15.99 (reg. $19.99). They were NOT the ones pictured in this thread. They had flat beds and angled sides with wide gaps at the corners. I almost pulled the trigger on them, until I saw enough negative reviews that mentioned thin steel, lightweight, "foil is better", warping, "twisted like pretzels" and such.
What I think I want is a basket that has a fairly large flat surface with small holes or slits. Most of the baskets seem too small to spread out multiple thin onion slices to grill and slightly char. I have also ruled out the baskets with the round holes that look like notebook paper holes. I think that we might lose some of the onions and other foods through those larger holes. Slits or tiny holes would be better, I believe.
We could spend the money for the Weber Crafted Roasting Basket, which is large and flat and has the right slits, but it costs $110. The price is more than I care to pay for a grill basket, and the size is too large for our needs.
I'll keep looking until I find the right basket, thank you.