Fixed tap basin wrenches do not come in sets as they are designed for a single purpose: to remove backnuts. Because backnuts rarely come in sizes other than 1/2inch and 3/4inch BSP there is no need to have a set of wrenches.
Adjustable basin tap wrenches do not come in sets because they are usable on a wide range of nut sizes and fittings.
Some, however, are available with a set of spare jaws in various sizes which increase the range of nut sizes they can be used on.
Box spanner basin tap wrenches are available in sets and come in a wide variety of sizes, from simple 5-piece sets to larger 30-piece sets.
Sets typically contain box spanners of sizes matching the most common size of plumbing fittings. The 7-piece set pictured contains sizes ranging from 8mm-22mm.
These multi-purpose Stiffnuts box spanners are available in sets complete with various attachments specifically designed for use on stubborn or rusted nuts and fittings.
The Stiffnuts box spanner allows you to undo or tighten stubborn nuts by using the mechanical advantage of tap tail thread.