Pet Shop Boys
Even though they are still recording to this day, most probably think of them as 80s music, and while my love for 80s music is no secret (see: my 80s Song of the Day thread!), most of those 80s songs I have nostalgic love for, are by artists I either have only one album by (like a greatest hits or something) or none (meaning, I bought those old hits from amazon or iTunes for a buck). But in the case of Pet Shop Boys, I own, I think, 5 or 6 of their physical CDs (and most of the others on mp3). That is by far the most music I have by any artist that would be described as synth pop, electronic, or dance.