I have Dell XPS 13 I7 6560U @ 2.20 GHZ with 8 gigs of Ram. No, its not a hardcore laptop by any means. I am intending to use some graphics hungry software like TOPAZ denoise or sharpening to edit my work.
I need a decent external GPU unit which can handle such applications.
I think it would be better to buy a used PC + GPU
But can you really trust a used setup?
Most eGPU boxes start at around $400 without a GPU included; and then you have to ensure your laptop has the proper bandwith (Thunderbolt3 etc) to drive it. You can cheap out with a DIY solution running from a miniPCIe slot underneath - but this ALSO has fussy requirements for compatibility and is less portable.
Instead, I'd save your $400 and put it towards a basic desktop setup (e.g. Techfast's deals) with a decent GPU. $800 would get you something with a 1660, and you could go all the way to a 3070 for about $1700 which is really futureproof.
Requirements are desktop CPU? I7 6560U is a lot slower than desktop i7 and even i3.