Get a Noctua cooler you won't be let down. And after eBay and possible shipping charges you may end up paying way too much for an average cooler.
Mod the top panel. I didn't look up the slot cooler you mentioned but if it's anything like I'm thinking it's not going to worth it. Blower type fans are notoriously loud but do move a ton of air. You will also be losing a pci slot, not that many average people fill all seven slots in a mini tower. Modding the panel will give you better performance at a mug lower noise level. But if you don't want cut up the top Lian Li does make a fan bracket for those slots by the pci brackets. A few of the members here use them and I think it may be linked on the first page of our club.
Thank you a lot! You shared some very important info with me! Can I ask - what does that "fan bracket mod" mean? Where exactly can I put fans to exhaust without cutting the TOP panel? This is the part I didn't quite understand. I checked the first page of this topic, but I didn't find any photos. Can you give me more information?