Harry loved buying gifts for Draco. There was something fun about finding things that The-Boy-Who-Had-Everything didn't have. Whether it was the fastest broom on the market, or a trip to an exotic location, or a vacation home in Milan, Harry insisted on nothing but the best for his Draco. He knew that there was no need. Draco could've bought these things himself. But Harry wanted to be able to give Draco anything he wanted. As well as some things he didn't know he wanted.
Maybe it was because he'd never had gifts as a child. He'd barely had what he needed, let alone what he wanted. Maybe it was because Harry wanted to be able to provide Draco with the lifestyle that he was accustomed to since birth, regardless of the fact the blond was wealthy enough to not need Harry's money.
Hermione was certain that the reason was that Harry had a deeply seated psychological fear of losing his loved ones, or being taken from them. She thought that he subconsciously wanted Draco to always have something with him or around him that would make him think of Harry and remind him that Harry was thinking of him in return. Harry had no idea if this was true or not, and he frankly didn't care.
But there was definitely one reason why Harry enjoyed bestowing random presents on days with no real significance: Draco's reaction. He loved hearing him laugh at something silly Harry had purchased. He loved seeing Draco's soft, wistful smile at something sweet he'd received. He loved Draco's indignation at receiving gifts that the blond apparently thought were better suited for a girl.
Yes, Harry loved buying gifts for Draco. The reason didn't really matter.
Draco loved getting gifts from Harry. But Harry never knew what his significant other's favorite gift was. For Draco, it wasn't any of the things Harry had given him; it wasn't expensive in the least. In fact, the gift he preferred over any other actually cost Harry nothing. Or maybe it cost everything, depending on how it was viewed. Harry gave it every night as Draco lay in his arms drifting off to sleep. It was nothing more than a gentle kiss on his forehead and the words,
"I love you."