This is a nice umbrella box, $29.95 US
for the pair. Steve Kaeser Enterprises also has an Amazon storefront. I have used a pair of these and similar Lastolite Umbrella Box units since 2007. I prefer these to the more-costly Lastolite Umbrella Box model, which is heavier, and uses a three-ziper closure as opposed to the drawstring closure these use.
Pretty hard to beat a pair of 42-inch umbrella boxes for under $30.
Softbox Umbrella Reflective 42inch
This type of modifier, a reflecting umbrella with a diffusing face on it gives what I call double diffusion; first the light hits the inner bowl and is scrambled a bit, and then that light goes through a close-in diffusing panel, softening the light additionally. This creates a softer light than either a shoot-through or a plain reflecting umbrella. One gets much of the benefit from a softbox, but without the need for a mounting ring, and with almost instant set-up, plus easy teardown and transport.
As far as umbrellas go, there are so many different sizes and types. Inner linings on reflecting umbrellas do change the light quality quite a bit: soft-silvery white-colored fabric is the norm, but there is also metalized silver, gold-and-silver or zebra, gold metalized, and also one of my favorites, the hard to find dull,matte white vinyl interior. You might find that silver-lined umbrellas make the rounded planes of the face light up a bit, which may be considered too specular in color images, but which adds a sense of dimension in B&W conversions. Also, smaller reflecting umbrellas give more contrast to the light than do big umbrellas, and that too can look good in B&W conversions. Thirty and 32-inch umbrellas have more usefulness than many people give them credit for these days, and work great with speedlights and quick setups. I like 32-inch umbrellas, and I like 40- to 43-incher's as well.