So I think, thus far, my two favorite consoles for shmuppin' are the NES and Genny. Don't throw a brick at me; I don't own a TG-16/PCE yet, otherwise I'm sure it would take up the #1 spot. Anyway, Genny shmups tend to be on the slightly pricier side (the good ones, anyway, a la Sagaia, Air Buster, Lightening Force, etc). NES games are typically pretty dirt cheap, and shmups are among the cheapest!
Here's the catch...I already own a great deal of shmups for the system. Here's a list:
Gradius
Life Force
Xevious
Galaga
Galaxian
Recca
Crisis Force
Tetrastar The Fighter
Fantasy Zone (both the Tengen and Sunsoft Famicom versions)
Geimos
Sky Destroyer
Image Fight
After Burner (Sunsoft)
Gyruss
The Guardian Legend
Defender II
Captain Skyhawk
Section Z
Sky Kid
Sky Shark
Terra Cresta
Zanac
Z Gundam Hot Scramble
Macross
Star Luster
*phew!* Well, needless to say, I'm starting to run low on good shmups to purchase. My one remaining "true" holy graisl are Uchuu Keibitai SDF for the Fami, which is rare and quite expensive, and Falsion for the FDS, and...I don't have a disk system.

Anybody have any suggestions for a quick 8-bit shmup fix? I don't usually take to the "jet-pack hero" style ones like Section Z, Abadox, or Burai Fighter, but I typically love anything with mechs, space ships, fighter jets, prop planes, etc!