If you have any idea what brands/models the guns & kit are, it would help you out immensely when it comes to selling them. Depending on condition, you can usually ask for about 70% of the retail cost, or lower, depending on how quickly you want to sell them. Selling it as a bulk lot at a discounted price may also be beneficial if you are looking to move it all quickly. If you only have a rough price, you can put that & state that you are also open to offers.
Whenever you are ready, head to:
https://airsoft-forums.uk/classifieds/
and there you can submit your advertisement posts for what you want to sell. List any/all accessories the guns/gear comes with if possible. Decent photos are certainly appreciated.
If preferred, you can state that you want it to be collection only in the description (best to give a rough idea where you are located) or you can also post. Posting gear and whatnot is fine to send via regular Royal Mail (recommend posting by either 2nd or 1st Class Signed For), but sending guns is a slightly different process.
After putting them in boxes & wrapping them securely (recommended), cover the boxes in either packing paper or bin liners (my personal preference) and make sure everything is taped. Stick the recipient's address on there, as well as your return address on the back, in case the delivery is unsuccessful.
To send airsoft guns, I heavily advise you send them via Parcelforce Express48. You must post these in person at the post office & declare the contents as a 'Low Powered Air Weapon'.
Do not include any batteries or gas inside the package (prohibited items) and if you have gas magazines, be sure to unscrew/remove either the fill valves or release valves of the magazines so that they are not pressurised.
Use PayPal Goods & Services when buying/selling & keep all receipts, in the event of something going wrong.
There are various other sales forums or dedicated sites which have airsoft classifieds/second hand areas, such as ZeroIn (not ZeroOne) & Prefired.
Sorry for the wall of text, but that should cover the basics.
Best of luck to you & your sons!
