I too have an SQB that I love, but my interests are more around the standard and wide end of lenses.
Just checking the bay, a 200mm lens starts at £120.00 including p/p and a 500mm starting at about £420.00, with both prices depending upon your camera model and mount, with a 'mint, new' 500mm one costing a few £1000's:
https://www.ebay.co.uk/sch/3323/i.ht...a=1&_dcat=3323
https://www.ebay.co.uk/sch/3323/i.ht...a=1&_dcat=3323
Terry S