3DS XL Case - Mario Lux only £4.00 at Tesco Direct (click & collect)
The 3DS XL may be a clamshell, but it's not indestructible and can be vulnerable to scrapes and scratches if you carry it around loose. Thankfully protecting it has rarely been cheaper thanks to this incredibly cheap case, which comes complete with snazzy Mario design. room for 3 game cards and a stylus holder for only four quid.
I honestly can't guarantee if it will fit the New 3DS XL, but considering that the dimensions are largely unchanged, chances are it will. Thanks to ssc1 @ HUKD!