Do you want to build this deck IRL or in the online game? I'd say it's expensive either way, but it's way easier to build online with a lower budget. This is because in this game we treat packs as a currency of sorts, and pack codes are (as you would expect) cheaper than the actual 10 card pack. Then there's also the fact that you can farm packs within the game by playing Events (tournaments). Do note that the packs that are sold in the in-game store for 200 Trainer Tokens are locked though (meaning, they can't be traded).
Incidentally (assuming that you're building that deck IRL), do you already have the cards in the list you posted? If you already have 2 Rayquaza-GX that's already 2 expensive cards you don't need to worry about having to buy. Anyway, I'll show you a list and an approximate cost of it.
[NOTE: Anyone who is more experienced than myself at trading and selling IRL, feel free to correct anything I get wrong. I'm mostly basing myself on Troll and Toad prices. It's been a while since I've built a deck IRL myself so some extra advice would be appreciated here]
****** Pokémon Trading Card Game Deck List ******
##Pokémon - 13
* 4 Rayquaza-GX CES 109 (13 USD x4 = 52 USD)
* 3 Grubbin SUM 13 (~1 USD)
* 3 Vikavolt SUM 52 (2 USD x2 = 4 USD)
* 1 Marshadow SLG 45 (1 USD)
* 2 Tapu Lele-GX GRI 60 (21 USD x2 = 42 USD)
##Trainer Cards - 33
* 2 Energy Recycler GRI 123 (~1 USD)
* 1 Escape Rope BUS 114 (~0.5 USD)
* 3 Mysterious Treasure FLI 113 (1.5 USD x3 = 4.5 USD)
* 1 Nest Ball SUM 123 (~0.5 USD)
* 4 Rare Candy CES 142 (1 USD x4 = 4 USD)
* 2 Rescue Stretcher GRI 130 (1 USD x2 = 2 USD)
* 1 Switch SUM 132 (~0.5 USD)
* 4 Cynthia UPR 119 (6 USD x4 = 24 USD)
* 4 Guzma BUS 115 (4.5 USD x4 = 18 USD)
* 2 Lillie UPR 125 (~1 USD)
* 1 Pokémon Fan Club UPR 133 (~0.5 USD)
* 1 Volkner UPR 135 (~1 USD)
* 3 Choice Band GRI 121 (~2 USD)
* 4 Ultra Ball SUM 135 (1 USD x4 = 4 USD)
##Energy - 14 (probably somewhere between 1 to 2 dollars total)
* 7 Lightning Energy 4
* 7 Grass Energy 1
Total Cards - 60
****** Deck List Generated by the Pokémon TCG Online www.pokemon.com/TCGO ******
Doing a rough estimate, you'd be looking at a total cost of around 165 USD. Now, a couple of things you should note:
> There's a significant portion of this investment that comes from staples rather than the cards that are unique to Rayquaza-GX. 4 Cynthias is pretty much a must in Standard (I'm a little skeptical on the 6 USD cost since it's pretty much the Sycamore of the old rotation but a lot more expensive, but it's what Troll and Toad says. It could have to do with the fact it only has 1 normal, non-FA print). Guzma is also a must, although the exact number will depend (3 looks like good enough to me, but this list included 4). Ultra Balls are also a must in literally every single deck. Finally, Tapu Lele-GX is also somewhat of a necessity in most Standard decks.
> If you haven't obtained the Cynthias yet, buying the Theme Deck Mach Strike looks like a good idea; the deck costs around 13 USD, so with the 2 Cynthias it has alone you've already recovered 12 USD. It comes with some more staples you can use too, and whatever you don't want to use you can sell or trade.
>If you're thinking of building this online, most of the prices are equivalent, but Cynthia is much more cheap than it's physical counterpart. You can easily farm 1000 Tokens and buy 2 (tradelocked) copies of Mach Strike, which gives you a pretty complete set of staples that you can use in every deck, including 4 Cynthias.
>This decklist does not include Zeraora-GX, which in my opinion it should include 1 or 2 copies of. The GX attack can potentially help you bring a game back when you've had most of your energies discarded (meaning, the Rayquazas they were attached to were KOd). The ability though is what you'll get more use out of early on though, since free retreat on any Pokemon with a Lightning Energy attached to it can be very useful.
So the next thing would be to think about a possible Charizard deck. It doesn't seem like you'll be lacking in damage at all since against GX focused decks you'll be doing a minimum of 190 damage (and even against non-GX decks you might end up doing at least 160 damage since most people play a Tapu Lele-GX early on without much of any means of removing it from the board). Being non-GX yourself, you have the benefit of only giving 1 prize at a time. However, there's a couple of big concerns:
> Just by being a Stage 2 deck, it's considerably slower than other popular decks. And, because of the attack's energy cost, this is possibly a double Stage 2 deck, since you need something like LOT Blaziken to charge your benched Charizard. In a deck like this, your main goal would be to bench at least 2 Charmander and 1 Torchick turn 1, and ideally evolve them straight to stage 2 the next turn. This is rather hard to achieve without the right card, which brings me to the next issue:
> On a double Stage 2 deck you would really, REALLY want to have Fairy type Alolan Ninetales-GX in it, which allows you to search any 2 items you want from your deck upon evolving. This is the only way I can think of consistently obtaining the 2 Rare Candy on your second turn. The issue? Alolan Ninetales-GX is stupidly expensive (the regular art one costs 26 USD a piece; buying the 2 you need would cost you more than what you could have saved by not buying a playset of Rayquaza-GX, which defeats the purpose of going with the "cheaper" deck). You can absolutely build this deck without Alolan Ninetales-GX, but you'll lose some consistency. If I could think up of a better way of accelerating fire energies without using another Stage 2 Pokemon this would probably work better, but right now I can't think of anything. Anyone else reading this is welcome to add some ideas.
Anyways, this is what I can think of for now. Let me know what you think, and I'll give you some more ideas.
EDIT: One thing I forgot to mention. If you intend on playing online I can help you obtain some cards. I'm a little short in packs right now, but I should be able to give you some staples to get you started.
Edited by Sakura150612, 25 December 2018 - 11:50 PM.