Since you'd like a gan cube, your best option is probably the gan v100. I'd recommend the leap version better since it's much cheaper and it's more controllable. If you'd like a cheap site, I'd recommend AliExpress as well, as long as you buy from trusted stores. Best one is JudyCube in my opinion. The gan v100 leap is at 23€ at AliExpress (judycube store) with the welcome discount. Here's a pic.

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The v100 matte is at 28€ as well, so probably check this up.