Your perception is that he was pressuring you. His perception might be very very different. Ask him, talk calmly with him about the shopping trip. Explain how you felt that led up to your being annoyed.

He may have been trying to make the shopping trip a time of togetherness, and wanted to decide *with you* which lava lamp to buy.

Open the door to allow him to know you and understand you. Be honest without being accusatory ("When you kept coming around to suggest different lamps, I felt pressured and judged. Which lamp we bought was important to me and I needed time to consider the ones we saw.")

Keeping feelings in makes us feel awful. Expressing them calmly is a way of standing up for your wonderful self. Others may feel differently, but that's about them. We all get to be ourselves.

I think your Dad would love to know more about you, in a deeper sense, meaning what you feel and what is important to you. You can give that to him as a gift that only you can give