You can either do multiple blizzard item queries using semicolons: rugged leather/exact/max-unit-buy/17s;fused wiring/exact/max-unit-buy/1.75 etc.
or you can do a single query like you did and use item post filters
by the way, the and/or operators have changed. you now type the number of arguments after the operator (e.g., or3 for a 3 parameter or) and if you leave out the number the operator will consume everything that follows. Also you need and operators to bind the prices to the items. your example would be written correctly as follows:
trade goods/or/and2/item/rugged leather/max-unit-buy/17s 0c/and2/item/fused wiring/max-unit-buy/1g 75s/and2/item/elemental earth/max-unit-buy/75s/and2/item/elemental fire/max-unit-buy/1g 20s
By the way, the filter tab in the newest version has received some nice upgrades, especially the post filter editor. You can use the mouse wheel to change the size, you can move the view by dragging if the filter gets too large to show all at once, you can right click individual filters to remove them and you can left click a filter to insert new filters there (the selected one is marked green)
you can also use the "import" button to show your searchbox query in the post filter editor nicely formatted to check if it's correct.
[video=youtube;kVm-LGOEJKc]https://www.youtube.com/watch?v=kVm-LGOEJKc[/video]