Maybe the Asmodus Lustro 200W?
The dimensions are 40.5mm wide, 36mm deep, 80mm high.
Guardianvape have the Purple Mod and a few other colours listed for £25.99, but I've never bought from them before
3fvape have quite a few listed - in several colours that may suit you. It is a Chinese site, and I think Paypal isn't available (because of Paypal/US politics rather than the site being untrustworthy), I've bought from them in the past several times without any problems but you will be looking at 2 - 3 weeks delivery time, and there is a possibility you may get stung by customs.
It is worthwhile to exercise your Google-fu and have a good search because the colours you like don't tend to move off the shelves too fast and they tend to sell pretty cheap. I saw a pink one last year for £20 but sadly its gone now, but if you look around you may get lucky.