Most of the rest of the world seems to think that video game music is inane and stupid. Ha. Their loss, in my opinion. Castlevania has some of the best video game music in history of everything, challenged only by anything Squaresoft and Falcom has ever put out. This section has information on all of the Akumajou Dracula soundtracks made in Japan.
The best place to look to buy game music CDs (Castlevania and otherwise) is Game Music Online, as they're quick and reliable, and have plenty to choose from too. Also, check out CD Japan as they have a lot of CDs for retail price (although, since they're located in Japan, the shipping prices can get a bit steep.)
CDs:
Castlevania Lament of Innocence Sampler CD/Japanese Limited Edition/OST
Akumajou Dracula Mokushiroku Castlevania 64 OST
Akumajou Dracula Best
Akumajou Dracula Best 2
Akumajou Dracula MIDI Collection
Castlevania Chronicles: Akumajou Dracula
Dracula - Castlevania: Circle of the Moon/Concerto of the Midnight Sun
Dracula Music Collection
Dracula New Classic
Dracula Battle Perfect Selection
Dracula Battle 2 Perfect Selection
Dracula Perfect Selection
Dracula X/X68000 Arrange
MIDI Power 3.0 - Gradius 3/Akumajou Dracula
Dracula X: Nocturne in the Moonlight OST
Dracula X Remixies
Konami Famicom Music Memorial Best Vol 3.
Konami Game Music Collection Volume 1 Haunted Castle OST.
MIDI Power Pro 6 - Dracula X
The Minibosses
Various CDs with Castlevania music
Game Rips