The other option would be a gas airsoft pistol as there are better sub £100 options available, but then you have the cost of gas.
The ASG Mk23 in two tone is £68 on Patrol Base, and although I've never used one they seem to be well regarded. I'd assume it has the same super long trigger pull that the Tokyo Marui one I own does though....
There's a few guns in this price range, but I can't vouch for which ones are good and WE seem to have rebranded 28 times since I last bought anything lol.