The seller is respsonsible for getting an item to the buyer.
If the item is big and/or bulky so that packaging is very difficult, it is sometimes best to offer the item for local collection only.
eBay
eBay or craigslist
Bicycle baskets can be purchased from bicycle stores, bicycle parts specialty stores, secondhand stores and from various sites on the internet such as eBay.
One can purchase bicycle lights from a number of places. They can be purchased from Amazon, ebay, Revolights or Walmart. They should be easy to fit to any bicycle.
Craigslist, eBay, yardsales
Try eBay
Amazon overstock walmart ebay bicyclecards.com
One can purchase a bicycle headlight from various websites like Amazon or eBay. One could also visit a local bicycle store and ask if they have any bicycle headlights for sale.
Bike stores, ebay, craigslist, classifieds ads...
One can buy high pressure bicycle pumps online. Some of the useful websites are Amazon, eBay, Lezyne, Halfords, Blue Sky Cycling, Sears and Bicycle store.
Most bicycle parts are actually generic, so they should be available from just about any bicycle store. Anything real special, then you have to hunt for it at ebay, craigslist and similar.
You can try to get them through the website of the manufacturer. They may also be available on some sites such as eBay.