The cost of a phone depends greatly on the quality and the features the phone has. You can purchase a basic corded or cordless phone for $10 to $20. These phones only allow you to place and answer calls.
To get a phone that is loaded with features like speaker phone for example, you should expect to spend anywhere from $50 to $150. These phones are better quality in addition to having more features.
If you are in the market for a new cell phone and are willing to sign up for a new plan or renew your contract, you can get a free phone with cheap phone service. If you are simply looking for a replacement phone, you should expect to pay anywhere from $50 to $500 depending on if the phone is new and how many features it has.