I'll kick us off with an absolute banger...
Boyzone - Love Me For A Reason
I was like 6. I wanted it desperately. Listening back to it now, as a 36 year old man I can admit that it's an absolutely horrible bit of music....but it still takes me back to being a young kid.
Right. So. I'm and old fart, and the first 7 inch single I bought was "I Wanna Be A Winner" by Brown Sauce when I was 8 or 9. A pile of crap written by B.A. Robertson and performed by a fake group of Noel Edmonds, Keith Chegwin and Maggie Philbin. The B-Side had the theme from Swap Shop, for it was some sort of Swap Shop tie-in. Unfortunately it wasn't the good theme for Swap Shop, it was a crappy one they used for the last season. The second single I bought was "Dead Ringer for Love" by Meat Loaf. Which was somewhat better.