Racketboy has articles listing titles and even a vs. article that answers this post, but I thought I'd float the question again to capture impressions circa 2011.
Which system, between the PS1, PS2, Saturn or Dreamcast, would be the cheapest to start an import SHMUP collection for? Assume I don't have any hardware or software already. I don't want to modchip or pirate and I only want CIB titles. I can live without the top 1 or 2 or 3 most expensive titles for each platform but I do want a decent collection eventually (10+?). I've used Yahoo Japan auctions before and am reasonably comfortable with it.
Thanks for the feedback so far. I've bought most of the PCE SHMUPs that the Wii Virtual Console has, so there might be too much overlap to buy real NEC hardware. I probably am looking for pristine hardware. I didn't know there was an easy bootdisc region crack- thank you.
If you go the PS2 route then you could play backward compatible games for PSone too. You said you don't want to modchip so maybe you could use Mcboot. I've never used that so I'm not sure if it will let you play PSone imports as well as PS2.
The problem with finding the cheapest import system for shmups is that shmups just aren't cheap on any system. Resale value is always going to be high because it's such a niche genre and the print runs are pretty low. Dreamcast might be your best bet as a lot of DC shmups actually got US releases.