Advice

I posted recently about my spilling a drink on my mac, I went to Apple and the guy basically told me due to the liquid damage obviously the components need to get replaced because there’s rust already. I should just get a new computer because that’s what it cost to get it fixed through Apple. I financed the computer through Best Buy so I’m literally paying it off still unfortunately and I can’t if I can afford to get a new computer and trade this computer in to Best Buy. The guy said to me I should take it to Best Buy and trade it in, they should give me around $600 for it but that requires to have more money that I don’t have. He told me if I take try to take it some third-party to professionally clean it that voids Apple from working on it I feel like I’m just stuck and I don’t know what to do. Any advice since I’m feeling very overwhelmed and stuck now?