I'm with the others on this ..... up to a point. "I'll take it" means exactly that. You are first in line. If payment terms were not specified in the posting, then the member with the "I'll take it" is still first in line while payment terms are negotiated, If payment terms cannot be met by the "I'll take it" member, then the seller is free to move on. I think everyone agrees so far with this particular example.
But what if a member posts the first "I'll take it" and stands ready, willing and able to meet all of the seller's terms and then the item is still sold to somebody else? I loathe deals that are done "in the dark", meaning through private messages. There is no transparency for the buyer. I have lost out on several transactions on items that I had been looking for in the following instances:
1) I was the first "I'll take it" on an item, but the seller later responded to me and told me that he had sold to another member who offered him more through a private message. The buyer admitted in later PM's that the other buyer was behind me in terms of response time, but he liked the other offer of more money. In other words, the terms of the sale were changed after my posting to an auction by both the seller and second guy in line. We all know that auctions are not allowed on the site. Due to the lack of transparency, I was not even aware it had turned into an auction. I would have gone higher on my price, but was never given the opportunity to outbid the other member.
2) Same situation as above, but seller was later contacted by another member through private message that was local. The terms of the sale were changed "behind closed doors" and I was left standing outside with payment in hand wonder WTH just happened?
3) Same situation as above, but seller sold the item to another member because he was able to get a response back quicker from him. After I had posted an "I'll take this", I sent a private message to seller to arrange the payment. Several guys jumped in behind me saying "I have seconds", "I'll take this if the others fall through" etc. I kept checking back over the next hour for a response from the seller. When nothing popped up, I left the house to run a couple of errands. I returned a couple of hours later to find the items had been sold to another member. It turns out that the seller had contacted all parties that had responded to his posting and then agreed to sell the item to the first guy that reponded to his private message. I get moving in line to the next guy if the first "I'll take this" poster does not get back to the seller within a day or two. But having the rug pulled out from underneath him for not staying glued to the computer for a couple of hours??
4) Same situation as above, but with another member responding sooner than me in terms of time stamp. Difference was his offer came via private message and was conditional based upon getting some answers to his questions. My offer was public and without conditions, thus meeting all the terms of the sale. This example has more grey to it, but the end effect was the member with the private message 'froze' me out for several days while he decide if he would move forward with the sale. I was willing to take the item as is. I had know idea this was happeneing and I spent several days waiting for a response to my "I'll take it" posting. In the meantime, I came across the same item for sale on another site. I passed on that item because I had already committed to buy the item on this site. I ended up with neither item.
With these life experiences under my belt, my position is as follows: "I'll take it" means exactly that. I will take it exactly as offered with all terms (including payment) willing to be met by the buyer. Posting and selling items openly in a thread is the only way to ensure that all parties involved can see that everyone is being treated fairly. It also provides a strong disincentive for buyer or seller to do anything underhanded, as everything is out in the open where other members can and will call them out. In summary, threads are for posting and selling items, while private messages should only be used for asking clarification or additional info on the item and for arranging payment.
I understand the arguments brought forth by topcat265. But they essentially turn a classified into an auction, which is prohibited on this site. There is legal and then there is ethical. I have sometimes found they are not one and the same.
Again, this is just my opinion guys. I see lots of room for improvement on how things get sold here.