You are about 10-15 years too late.
All the eastern block surplus flares have been sold, or are now too old to work reliably.
If you really want parachute illumination flares, forget the gun and get the handheld SOLAS flares.
$37.99 at West Marine
You can sometimes find someone selling out of date flares (Over 3 years) from commercial ships for $1-5 each.
IKAROS Red Rocket Parachute Flares
The IKAROS parachute rocket was introduced in 1959 and its design is now used by most manufacturers around the world. IKAROS is the leading parachute rocket on the market with quality and performance that meets the highest demands on functionality and safe operation. It is approved globally and conforms to the latest SOLAS 74/96 regulations.
This day or night long-range distress signal ejects a red flare on a parachute at 350m (1150ft), burning for 40 seconds at 30,000 candela and visible up to 30 miles. The IKAROS parachute rocket is waterproof and can be held under water in the ready-to-fire position. Dates on these flares are 2013-2014.
$19 each at flaregunsales.com