Could you possibly consider making a slightly better offer?

가능하다면 조금이라도 더 나은 제안을 검토해주실 수 있나요?

• Could you submit a better offer?
• Would you be able to put forward a better offer?
• Could you please reconsider a slightly better offer?
• I'd appreciate it if you could consider making a slightly better offer.
• I'd be grateful if you could consider making a better offer.