could you help me with this Gladiator Beast deck?

Whilst I can't recommend a cheaper way of building it, I can certainly recommend a better way of building it.

Most builds focus on the use of Test Tiger with Prisma to bring out Gyzarus in the early game, which sometimes works, and sometimes doesn't. It is powerful, but inconsistent. Without the Prisma engine though, it is pointless trying to run the deck the same way.

The biggest problem you have at the moment, is way too many monsters. You are running 20 monsters, out of which 17 are Gladiator Beasts, on top of that though, you have 5 monster searchers, which will search out Gladiator Beasts, so you are effectively running 22 Gladiator Beasts, 22 monsters which will shuffle themselves back in to the deck.

Most decks run quite a few monsters on the basis that if you run 20 monsters you will draw into half monsters, and half spell/traps, but as the game goes on, your monsters are more likely to stay on the field, whereas you will use your spells/traps, so you want to draw in to more of them. However, when you try this with 22 Gladiator Beasts you find that you will keep on drawing in to Gladiator Beast monsters, because you always shuffle them straight back into the deck.

The build I run is far, far more consistent than the Prisma/Tiger build, but admittedly has a worse early game. In my experience however, consistency is more important than power. It's all well and good having Prisma and Test Tiger, but when you are top decking and draw in to a lone Test Tiger, you have lost, when I'm top decking, I draw in to Pot Of Duality, I actually have a chance. By not relying on combo pieces, each card in your deck can stand alone.

Anyway, this is how I run Gladiator Beasts (to great success might I add)

Monsters: 10

Laquari x 3

Darius x 2

Equeste

Bestiari

Retiari

Murmillo

Fire Fist - Bear

Spells: 22

Proving Ground x 3

Tenki x 2

Tensu

Pot Of Duality x 3

Respite x 3

Upstart Goblin x 3

Onslaught Of The Fire Kings x 2

Dark Hole

Book Of Moon

Forbidden Lance x 3 (If you really can't ahold of these, Enemy Controller/Shrink can do the same job, just worse)

Traps: 8

War Chariot x 3

Mirror Force x 2

Bottomless Trap Hole

Torrential Tribute

Solemn Warning

The extra is just 2 Gyz, 2 Herak, 1 Essedarii and then rank 3 and 4 xyz monsters.

The basic idea with this deck is draw power, you get everything you need to hand quickly, and then just play smart to maintain hand advantage. Instead of Prisma + Test Tiger, we have Onslaught Of The Fire Kings, it gives you a free summon from your deck, whether you summon Laquari with it and then normal summon Bestiari to make Gyzarus, or decide to normal summon Darius to make a rank 4 (including Tiger King, who then grabs a Tenki from deck)

Predominantly though, the deck works by using your knowledge of what to do. You have to play conservatively, especially with your traps. You don't just Solemn Warning the first monster they drop with more attack than your monster, you let it destroy your monster, then next turn you Forbidden Lance their monster, attack over it, grab Darius from deck to summon back your GB from grave and then xyz/contact fusion. It is probably one of the most important things in Yu Gi Oh, to learn how and when to play your cards, sure you save your monster with Solemn Warning, but if they drop BLS next turn and you have no answer for it, well that's game.