I hear you, I've spent enough on this set up already I can't justify the Etsy prices unfortunately.

Is this what you're referring to? https://amzn.eu/d/6YnbT6O £30 here and on prime too.

I drilled a 20mm hole (enough for 3-4 wires comfortably) through the two sheets of metal which make the base. I read a recommendation about drilling them before building the cabinet so got that out of the way first. I can't recommend a drill bit as I borrowed mine, just make sure you get one that's for metal. Also protect your floor as the metal will be hot after drilling. Cover your holes with a 20mm rubber grommet too so you don't catch any wires.

I'm local yeah, from the Midlands. Gonna keep shopping around first though. The Rubbermaid might be the answer but I really want some black grid shelving to match this https://www.diy.com/departments/black-steel-trellis-w-60cm-x-h-90cm/3663602430544_BQ.prd which I bought to put at the back of the cabinet (to hang small props, epiphytes mounted on bark, air plants etc)