Towel prices can vary. You're able to pick up cheap towel sets from Amazon that will cost less than $30 for a bundle, but there are also premium options with prices that span into the hundreds. A good bath towel, standard size will cost around $40, and you should expect prices of around $100-$150 for sets and bundles. Bath towel bundles typically include a bath sheet, bath towel, and face clothes at a reduced price as opposed to being bought separately. They're worth the money and it's always better having a spare towel you can swap out for when you come to wash them.
Great towels made of high-quality durable materials can last around 3-5 years, so it's worth spending more if you can. That being said, if you're looking to add interest to your bathroom with a bright-colored bath towel, opting for a cheaper option could be better.