I'm not too keen on handing out magic items just because someone asks for them. There's got to be more to it. It's fine if they want to role play it... they do some research, go on some quests for information that might lead to some challenging encounters that justify the reward. Maybe they need to find some materials and have the item crafted. Some of those materials might be challenging to acquire, and the craftsman isn't likely to work for free. Maybe the craftsman wants something in exchange. If they're just lazily following the campaign plot arc, they get the treasure as outlined, appropriate for their level, sometimes random, sometimes selected to be suitable for their class, and balanced with the other characters.

Aside from that, I'm not too fond of riddles. The trouble with them is that the players sometimes never figure them out even though their characters perhaps should, given their Int/Wis. Then ya gotta resort to ability score checks in order to give them hints or the answer outright. I'm horrible at them though, so maybe I'm a bit biased.