Lipomas on the scalp are usually removed by surgical excision. However, there are other causes of lumps on the scalp including sebaceous cysts and pilar cyst which can appear very similiar to a lipoma. These can also be removed by surgical excision and ideally sent for histological confirmation.
Surgery is usually done under local anaesthesia. The main complications are bleeding and haematoma formation, infection and scarring.
The duration and cost will vary according to the size and complexity of surgery. A ballpark figure is about 20 to 30 mins and cost $600 and up.
Hope this information is helpful for you.