New Urban Basing Kit from Spectre Hobbies

It includes 3 bases, so there's your answer: 3.

Just kidding. Obviously this kit is meant to enhance figures that are already based, and the 3 supplied bases are meant as extra bitz for figures that don't have them or for making counters or whatever.

The answer depends on how far we can stretch the items. This part of the list appears to be discrete items:

I Beam X-large
I Beam Large
I Beam Med
I Beam Small
Square Tubing
C Beam Small
C Beam Large
Chain
Diamond Plate
Wire Mesh
Rubber Tubing
Brick Wall

I count 12 items; we can probably assume one per base.

These items probably accent bases rather than being used singly:

Barbed Wire (1 ft.)
Rubble (7 Random Resin Pieces)

If we figure we use 2 inches of barbed wire per base, that's another 12-13 bases.

This stuff is for texturing:

Slate Rock (Natural)
Cork rubble/rocks
Sand – Fine
Sand – Coarse
Winter field grass
Modelling paste
Mineral Texture Gel
Scenic water

A quite nice collection.

And this is for general utility:

PVA glue
Free wood stirrers, 2 sizes
3 bases 30mm, 40mm, 50mm

Though one might be tempted to chop up the stirrers to make scale boards!

Anyway, it looks like for the $22 USD this kit costs, we get enough to make 12 interesting bases (each with a discrete item plus barbed wire or a rubble piece) plus a ton of texturing options and some extra bases and PVA glue. And I'd guess some of the texture material might be left over.

I frequently scoff at pre-made bases that cost more than a dollar each, and that cynical view would complain about this kit, but the other way to look at it is, for an affordable price we get a huge bitz box for basing.

I might pick this up at a show just because, and I don't even game modern.