Sennheiser has a pair of open-back, HD579 headphones on sale on Amazon for just $98.88. These are a great pair of headphones that typically cost around $150, so you are essentially getting these for around a third off of the regular price. That's not bad at all for a pair of Sennheiser headphones that rarely go on sale.
These headphones from Sennheiser are a pair of open-back headphones, which provide for a unique and more authentic sound. There are 38mm drivers inside these headphones, which provide full sounding audio, with deep bass, and crisp mids and highs. These are not Bluetooth headphones, so these are going to need either a dongle, or a smartphone that does have a headphone jack still - which those are getting increasingly rare these days. Sennheiser also provides a two-year warranty on these headphones, so you'll be covered in case something happens.
This item is also eligible for Amazon Prime's free shipping. Which includes free two-day shipping, and pretty cheap next-day shipping if you need it here extra fast. If you are not an Amazon Prime member yet, you can sign up for a free trial of Amazon Prime by hitting the link below. You'll get 30 days free (if you're a student, you get 6 months), and then it's $99/year. Prime members do get a whole lot more than just free shipping though, so be sure to check out the full benefits.