Walking to the post office is no big deal, but there's finding/buying the right size box, packing so it doesn't break, hoping you have tape, if not, buying some.. I hate shipping stuff..
If you wanna sell you gotta ship, Here is a quick lesson,
1. Put lens in original box,
2. wrap box in protective medium (bubble wrap, newspaper,old tee shirt,)
3. go to post office
4. Grap medium flat rate box
5. ask clerk for priority tape, and address label
6. assemble box
7. place wraped lens box in flat rate box
8. seal
9. attach label
10. hand box to clerk
11. pay
12. go back home and sit on your couch and rest.
box, tape, and label all free from post office, Fancy bubble wrap maybe a buck or two for a roll,
Not rocket science