Gray Blazer

Front button style: button two

Button stance: classic (buttons at natural waist)

Jacket length: slightly short

Sleeve length: classic

Front darts: yes (slight waist suppression)
Color: medium gray

Lapel width: slightly wider than classic
Lapel edge: swelled
Lapel style: notch
Notch height: slightly high (but not high by today's standards)

Jetted or patch pockets: patch
Flapped or flapless: flapped
Flap height: classic

Cuff button style: button one

Vent style: single
Vent height: deep (11"; classic height is 8-10")

Shoulder: moderately padded and extended 

A Southern California chain that went out of business in 1991, so the blazer can't be any newer than that.

Age verdict: late-1960's (or very early 1970's), for 3 primary reasons:

1) the late 60's were a transitional period between the thin lapels of the early-mid-60's and the wide lapels of the 70's;
2) Deep vents started becoming popular in the late 60's;
3) Although the button one front reached its apex of popularity in the mid-60's, the button one cuff remained stylish for a couple years thereafter, even on button two and three fronts. 

60's Black/Off-white Check Sport Coat

Front button style: button one

Button stance: classic (buttons at natural waist; I prefer a lower button stance, but this jacket was meant to be worn with pants at the natural waist, so it makes sense)
Button color: off-white (so it almost blends into the jacket rather than contrasting with it, as black would)

Jacket length: short

Sleeve length: short

Front darts: none (almost no waist suppression)

Lapel width: thin
Lapel style: notch
Notch shape: half-clover (straight on top, curved on bottom)
Notch height: classic
Chest pocket: none (perhaps the jacket's most minimalist touch, more so than the one button)

Color: black and off-white
Pattern: check (Does anyone have a more precise name for this check pattern? I've had two suggestions: "gingham" and simply "check".) 

Jetted or patch pockets: jetted
Straight or hacking (angled): hacking
Flapped or flapless: flapped
Flap height: short

Sleeve button style: button one
Button size: large (same size as the front button)

Vent style: double vents
Vent height: short (5")

Shoulder: somewhat padded and slightly extended (the only negative and element that's inconsistent with both the jacket's overall minimalism and the 60's American style)

Country of manufacture: USA

Anyone ever heard of this shop?

Age verdict based on all the above evidence: mid-1960's