I will be a broken record... assuming you have a good recipe, good beer depends on:
1. Good water, geared to the desired taste
2. Tight temperature control (and pH if so inclined) of mashing and sparging
3. Pitching healthy yeast at the correct temperature
4. Oxygenating to proper levels at pitching
5. Fermentation temperature control
6. Proper sanitation
7. Low oxygen exposure after primary has completed
These are the things that can be improved to get better beer. Some expensive equipment can help these things. As others have said, fermentation temperature control is an easy thing to accomplish and worth every penny. An expensive kettle probably won't do much. But if your friend really wants one, he should get it. Just tell him not to expect good beer until he addresses the important things.
1. Good water, geared to the desired taste
2. Tight temperature control (and pH if so inclined) of mashing and sparging
3. Pitching healthy yeast at the correct temperature
4. Oxygenating to proper levels at pitching
5. Fermentation temperature control
6. Proper sanitation
7. Low oxygen exposure after primary has completed
These are the things that can be improved to get better beer. Some expensive equipment can help these things. As others have said, fermentation temperature control is an easy thing to accomplish and worth every penny. An expensive kettle probably won't do much. But if your friend really wants one, he should get it. Just tell him not to expect good beer until he addresses the important things.