Reddit mentions of Frisk Acrylic Keep-Wet Palette

Something like this?

Having been painting for almost a year and still getting slightly better each week, I'd strongly recommend that if you want a 'collector's set' that you get some painting practice first.

It's a great hobby, but your first models will be messy. Heck, my last models have been messy. There is ample tutorials online, some official warhammer ones to, by Warhammer TV on youtube, but it would be unlikely that you will be a perfect painting right from the get-go.

Might be worth booking some painting sessions with your local GW, as that is something they can do. But if you want one brilliant army in battle against a few others, then maybe you could practice on one of its enemies. Stormcast and Blades of Khorne have the most (i think) official tutorials online, so you could get some of them to practice on.

Cost wise, excluding miniatures themselves, you would be looking at 3 or 4 brushes at minimum. The cost can vary greatly, Citadel (GW brand) tend to be sub-par. This isn't me GW bashing, I genuinely have tried a couple options and found them to be this way. I would highly highly recommend these though:
https://www.amazon.co.uk/gp/product/B0013E68T4/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1. I got the size 00 and size 1, and although the size 1 is big enough, it keeps a great point that you can use it as a detail brush. My 00 hasn't kept it's point, but still very good. Also, if you are doing Seraphon, you will need a drybrush. Normal brushes get wrecked after a few dry brushes. If you haven't heard, drybrushing is really good at bringing out raised detail in your models, particularly good with scales.

Wet palette is very useful, it will minimise your paint loss. Again, here is one I bought, but you can DIY one for yourself pretty easily with some kitchen towels and baking paper or something like that: https://www.amazon.co.uk/gp/product/B00J0CN8ZS/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1.

Pretty optional, but a good LED lamp with a flexible head would be a god send. You won't realise how yellow your lights are until you see a good LED lamp.

For working with plastics, you need some cutters, a file, a mouldline remover is pretty good too. GW does all of these, but again, premium price. You can probably get equally good versions elsewhere for less if you look around.

Also will need super glue and plastic glue. Superglue won't ruin paint, plastic glue will melt it but gives a better hold in the long run. Usually for trickier models, you might paint it first before assembling some of the more awkward bits. Bad explanation, but for example I left my shields off my models so that I can paint their arms. Then I superglue them on to not ruin the paint.

Frisk Acrylic Keep-Wet Palette
smile.amazon.co.uk/dp/B00J0CN8ZS/ref=cm_sw_r_fm_apa_i_SjCWDb9NACMQF

It's that one there (which is essentially just crap plastic but it's the perfect size) and then I use normal baking parchment and those thin sponges you can buy for cleaning. (They work way better than the paper and absorbent stuff in the box, I just bought the thing for the plastic tub)!