ITs obviously not the hiking boots!!
So when you prepare the listing when you get to the postage section there is a little button/symbol top right called postage options (I have pictured below) then towards the bottom click the little arrow to buyer collect in person, you can turn off the other options. There is also another bit at the bottom of the listing above preferences, collect in person, ensure (as a double check) its highlighted in blue.
Also ensure the item is cash on collection - it allows the buyer to inspect item before paying and taking the item away.
