Having witnessed a fair amount of confusion of late, well, at least since I began using both auction formats in the same week, I decided to offer a guide as to which auctions allow offers in hopes of helping those who are making offers that cannot be accepted only to see the auction end before they can make a bid that can be accepted.

There are 2 types/formats of auction in ebay, the Fixed Auction and the Biddable Auction, which is called Online Auction. ONLY within the Fixed Price Auction does the seller have the option of allowing the buyer to make an offer and that is determined while the seller is setting up the auction. 

There is the fixed price auction where the bidder has the option of allowing offers to be made or not.  You could have offered the $150 on that type of auction.  It shows the buy it now price and tells whether or not the seller will consider offers. If offers are considered, you can make an offer and the buyer has 48 hours to consider it and can accept, decline, or counter.  On some autions you can make more than one offer but it varies so you have to check ebay rules.  Stores use this auction format but are excluded from using the take offer feature

There is also the bidding auction, defined by eBay as Online Auction, which has the option of listing a buy it now price for the seller.   The seller pays an addition fee when setting up this type of action.   That type auction shows a starting price and a buy it now option if the seller has listed one.  It does not allow offers.  You have to use the starting bid or buy it outright at the buy it now bid.  You can't make offers as that is against the ebay rules for this type auction so the seller cannot accept an offer and end the auction early.  If there is a reserve price on this type auction, the buy it now price will stay in effect until the reserve price is achieved.  If there is no reserve price, the buy it now price option disappears when the first bid is made.  Remember that you need to bid right away if you want an option with a buy it now option if you are sure you are interested in purchasing the item but do not want to pay the buy it now price. Within this auction format, there are also live bidding auctions, which have a clanging bell icon to distinguish them for other auctions, where you have to register early to be able to bid and the auctioneer charges a surcharge to the buyer on all won auctions.  An aside: you can ask about the shipping costs and some buyers might cut them, in rare instances, if you live close to their zipcode or allow pickup.

I hope all this information helps you in your future auctions.  Good luck with all your bids.