Here's a direct repost from a shackpost complete with some ps2 stuff still in and no hotlinks (GreaseMonkey -> Install it). It's not complete at all (only US games) but it should give you a good jumpstart on what to look for locally.
I've recently been turned on to Harmful Park and I'm really trying to find a copy of Gaia Seed for under $70. A decent list is up on shmups.com which should provide a good starting point. You may want to read the forums there a bit as well (hell, register and post sometime)
I was never a big fan of Gradius III and Gradius IV is about as dull as they get :(
Shikigami no Shiro got butchered for its us release but it's not too bad for the price
The sequel, on the other hand, is fantastic and improves on the original in every way. the original cutscenes were left intact and were given a hillariously horrible translation. The gameplay is a lot easier to get into than the first game, the graphics are great, and the level designs are interesting. Plus it's only $10
Zanac X Zanac commands a high price because of its rarity, but it's totally worth it. It contains multiple versions of the original Zanac and the new Zanac Neo is fucking ace.
Shienryu got ported to the playsation as Gekioh and received a budget US release (~$10). Very enjoyable if you like Raiden (it's pretty much Raiden DX 2) but it has some annoying slowdown problems that aren't present in the Saturn release or the japanese/euro ps2 release.
R Type Final is another nice game, but it doesn't really compare to R Type Delta for Playstation 1. R Type Final will run you about $20 new now a days and R Type Delta you can score direct from Agetec for $30. While you're at it, get R Types as it includes both R Type and R Type II (both excellent games)
RType Delta: http://www.agetec.com/products.asp?MyView=Shooting&ProductID=43&ProductName=R%2DType+Delta
RType Final: http://www.amazon.com/exec/obidos/tg/detail/-/B00017X22U/qid=1105149055/sr=8-1/ref=pd_csp_1/103-5697129-7759040?v=glan...[amazon.com]
Speaking of Agetec, they've published a few other good shooters here. Sanvein gets ZERO love from most people, though Kiken released an excellent superplay video of it a few months ago. I picked it up on a whim back in 03 and haven't regretted it at all. Really different and really fun.
Strikers 1945 II got released as Strikers 1945 and I believe the major change was the omission of the TATE mode and the forced wobble mode. If that doesn't bug you, then look into picking up Gunbird (released as Mobile Light Force) at the same time, as it is from the same developer and has a similar play system:
If you can scrape together the cash, I recommend picking up Raiden Project, though it's getting pretty hard to find for cheap:
Raiden was rereleased as a budget title in Japan and Raiden DX has been released as a budget title, but if you want Raiden II, you need Raiden Project. Of course, if you imported Raiden DX then you'd probably never want to play Raiden or Raiden II for any reason other than nostalgia... but you still would need a mod chip :(
Einhander is the cat's motherfucking pajamas. You can't go wrong with that puppy. Difficult but very rewarding.
Philosoma is a weird little mixture of literally every shmup subgenre ever done into one product. Each stage is broken into substages and each substage is a different viewpoint. In front of the ship, behind, above, below, to the side, isometric, etc.
If you liked the gameplay of Tumiki Fighters, where you could use your enemies as pieces of your own ship, then you NEED G Darius, which is pretty much the high point of the Darius series (though I wobble on that one... it just depends on which game I've been playing the most of recently, Darius Gaiden or G Darius :) ). Awesome awesome game with branching paths, the ability to capture enemies, fantastic music and rocking hot graphics (for the time).
On a sidenote, the team that developed G Darius went on to form GRev and make Border Down on the Dreamcast.
Irem's In the Hunt made it to the US as well, though it's a bit heavy on the slowdown. Some pretty good action is still burried in the game (I correct the slowdown problems in MAME by overclocking the main cpu, but on the playstation you're pretty much shit out of luck). It's been rumored that members of the team behind In the Hunt and GunForce 2 would leave to form their own company and develop a little known game called Metal Slug, but those rumors mostly stem from gameplay and graphic similarities between the games.
RayStorm and RayCrisis, sequels to the excellent RayForce/Galactic Attack/Layer Section (on Saturn) aren't quite as good as the original but are well worth checking out. Basic gameplay includes the ol' lock on laser and two planes of movement to contend with at the same time (similar to Dragon Spirit, Xevious, etc)
ThunderForce V (sadly, the last of the series) was an excellent game on both Saturn and Playstation (though purists refuse to play the game on the Playstation because it's graphically inferior to the Saturn version), and sadly only the playstation version made it to the US (thanks to Dickhead Ireland's company). Good luck finding it for cheap, though you can always order it directly from AssPumper Himself: