Custom made? Mass produced? Exotic leathers? A lot of these threads you are starting have been started before and you can find them by searching. But I'll still play along. Firstly you get what you pay for. £20 range I would go for Keleran leather, maybe some Hirsch or Hadley Roma, and I think Watch Gecko sells some good leathers in this range. £40 range I would just save a little more and get something higher quality, like Crown and Buckle Black Label, or some stuff from custom strap makers (here on OF and Instagram). (More like 60-80-100) Or go £100-300 with Hodinkee's stuff, Bulang and Sons, Camille Fornet, Jean Roussea etc.