as per thread title, they’re banned on ebay, very little on gumtree. Where does one get one from?
Try http://www.guntrader.co.uk, good place to start. It’s illegal to purchase air weapons mail order (although it has only become so very recently) – you can only buy them over the counter from a Registered Firearms Dealer (RFD), or obviously if you buy one privately. You can order an air gun mail order, but it cannot be delivered directly to you, it has to be delivered to an RFD for you to collect.
& what’s the legality of shooting rabbits on public common ground
In England at least, there’s no such thing as “common land” – all land belongs to somebody.
If you want to go shooting rabbits, you MUST have the landowner’s consent otherwise you can get in big trouble.
If you don’t want to go through the rigmarole of getting an FAC, your rifle must be producing less than 12 foot-pounds of energy at the muzzle. If you buy your gun from an RFD they should chronograph it at point of sale to make sure that it’s legal; if you buy one privately, you should get it chrony’d as soon as you can. If it’s even a SMIDGE over that, then it’s classed as a firearm and you need an FAC. There’s no leeway on this limit either, and carrying an unlicensed firearm in public carries a mandatory 5-stretch.
See the BASC code of conduct HERE