I took my time and collected first print first editions of the paperbacks.
The PS was the hardest (obviously) it took me about a year to find a CoS but the PS took much longer because apparently a lot of people have ripped these out of their paper binding and bound it in leather - nasssty!
along the way I've also picked up a Ted Smart second print first edition Phil Stone with a very cool picture of a "different" Dumbledore on the back - this is the same Dumbledore as in the first and second print Bloomsbury editions which I'm proud of as it's pretty cool.
Yeah the "deluxe" editions are great, I have those too

if you just want a nice looking set of the books for your bookcase this is the way to go.
If you wanted to try to get the first prints of those you might be out of luck too

in this case the PoA was the one printed first and has some mistakes in it so that one's the toughie, followed by PS, CS, GOF and OOTP