Keep in mind that we are still in the verrrryyy early stages of testing this feature out. Not all sellers have this option at the moment, and it is something that has to be toggled on for the item by the sellers who have this option.
If you don't see this as an option when you're listing your item, it may mean that you aren't in the test group (yet.) Even if your personal account doesn't have this option for selling, you may still see items that are available for sale nationwide in your search results.
As there is so little info available on this feature, I write to share my experience. Earlier this week, I noticed that my app had the feature to allow me to search nationwide. On the left hand side of the app for the iphone, the app had an option to search locally and on the right handside, it had an option to search nationwide. The nationwide search feature was available on the app for about 4 hours. Thus the feature is clearly still in beta testing and is not always present. I made several offers using the nationwide search feature while it was available on my app. Here are a few observations. Many sellers did not realize that they had listed their items under the feature! As a result, when I contacted them, they pointed out that they didn't live in my area. Someone else on these boards indicated that shipping was free to the buyer. Not true. For each item, there was a shipping fee listed. In some cases for the items I wanted, it was $5 and in other cases it was $7. There was no indication as to how the shipping fees are determined. When you make an offer through the nationwide search feature, a seller has two days to decide if they want to accept your offer. After that the offer is cancelled and the app sent me notification of the cancellation. If the seller accepts your offer, your credit card is immediately charged. The seller then has 5 days from accepting the offer to send you a tracking number showing that the item has been shipped. If this does not happen in 5 days, OfferUp indicates that the offer will be cancelled. I had three of myoffers accepted by sellers using the nationwide search feature. I contacted all three sellers to ask when the items would be shipped. All three responded with a ship date. Thus far, only one seller has shipped the posted item. I am expecting to receive it next week. The other two sellers said they would ship by now but have yet to do so. I expect that both of these transactions will be cancelled for failure to ship within the 5 days from accepting the offer. I will post again with updates.
A couple of other points I failed to mention above. As the buyer, when you make an offer using the nationwide search feature, you enter your credentials (name, credit card #, and shipping address). According to the info posted by Offer Up, once you receive the item, you have 3 days to evalute it. Once the buyer "accepts" the item based on the evaluation, the sellter gets their payment. I could not find any information posted by Offer Up as to what happens if a buyer, based on the evaluation, does not accept the item. For example, if the item does not match the description, who pays for return shipping?