How many video game systems did you buy specifically because of a Castlevania game? This could also count as systems you may have been planning on buying eventually, but purchased much sooner due to a Castlevania game. Here is what I bought because of Castlevania:
Game Boy Advance - I know I would have bought this system anyway because of the Mario games, but once I saw Circle of the Moon and Harmony of Dissonance I immediately bought the GBA SP, and it remains one of my favorite systems.
Game Boy Player for Gamecube - I bought this GBA Player specifically to play the GBA Castlevania titles on TV, however I probably would have gotten this eventually.
Nintendo DS - I bought it right when Dawn of Sorrow came out. I still have the same original DS and it works great. It is a little bit larger than what they have out now. I know I would have eventually gotten a DS, but Castlevania is why I bought it so fast. This is also one of my favorite systems.
PlayStation 3 - I bought the PS3 and Lords of Shadow together when LOS was released. I was also happy that it came with a free download of SOTN for the PS3. Even though I have 2 copies of SOTN on PlayStation, I still had to beat it on PS2.
PSP - Bought this system because of Dracula X Chronicles, and I think the PSP is the worst system I ever purchased. I just don't like any of the titles they released for it. After I bought a PSP every time I looked at the games I saw nothing I was interested in. I am more of a retro gamer and am not interested in newer series like Call of Duty, or whatever else PSP was pushing. I was planning on getting Silent Hill: Origins, and the 2 Grand Theft Auto games they made for PSP (Liberty City Stories and Vice City Stories) but luckily for me they ported those games to PS2.
I can tell you that from my experience with PSP there is no way I am buying a Vita, unless they make some really, really awesome, exclusive games for Castlevania, Silent Hill, and Resident Evil. I already have a 3DS and bought it because of Mario Kart 7. This was the first time that Castlevania was not released before Mario Kart on a Nintendo handheld.