I write music on the side. IF I were to be getting headphones I'd get
Sony MDR-7506 (you can find these sometimes for $60 on sale at Amazon. Lowest price I've seen was like $35 on a Cyber Monday. But these are probably the best in class for sub $100 phones. I use them in my home recording studio)
Audio Technica ATH-M50X (lowest price I've seen is around $129). If you want to save money, you can get the ATH-M50 which is the same headphone driver without the three detachable cords.
Sennheiser HD-280 Pro (also had a pair of these).
For In-Ear monitors, I'd get some Shures.
As always, figure out what you want to buy and then use Slickdeals Alerts to get notified when a retailer is selling something at a really good price. However if this is going to be a Christmas gift you might not have time to wait for a good deal.