The summer sale is here once more, and that means Degica has shooting game bargains aplenty:

From Deathsmiles and Mushihimesama, to the DariusBurst CS Cave DLC and all the Cave game soundtracks. http://store.steampowered.com/sale/cave_interactive/

And for a more traditional shooting fix, Triangle Service has just what you need here:
http://store.steampowered.com/bundle/1293/Triangle_Service_Shmups_Collection/
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And if that's still not enough shooting action for you, our friends at Mages. have put their first foray into Steam shooting games on sale too, and there's a score contest with soundtracks and a T Shirt up for grabs during the sale too. So if you're looking for a fun, entry level game, Bullet Soul has you covered.

http://store.steampowered.com/app/544580