I can highly recommend My Art Broker if you decide to invest in art, especially Banksy prints. I have bought (and sold) several works by Banksy through them over the past 5 years including, recently, a signed Love Rat. Their service is excellent and I haven't had any problems with payment (in either direction) or receipt of PEST certificates. All the prints were in mint condition as promised and in my experience you can buy (and sell) with absolute confidence. I will definitely be using them again in the future.