I'm looking to buy one from a seller. I have no idea what the cost is going to be. Can someone help me out here? And to what other details I should go
Depends, ones with Zs and Qs and bad letters will be cheaper, but except to pay about $30-$50 for a decent one.
LLLL.coms, regardless of letter combination, are selling for $50+ now. Even if you had the name 'zqkv.com' or something it'd still be worth $50. Or, there would be someone who pays that much for it*. You can check out 4letternoob.com (awesome guide) for weekly price increases/decreases in the LLLL market. But, expect to pay $50+ for the name and $125+ if it's pronounceable/contains 3+ premium letters.
Really? I guess the last time I looking into 4 letter .coms was about a month ago and I could have gotten a few for $20. I should have bought them! Good point, if you are seeking out a domain, expect to pay more.