TL;DR get Pax, Falcius, Whisper of the Sands, and Inquisitor Kron/Aymara. Also upload your decklist
Hard to say what you should get next if you don’t have a decklist.
Generically, you would want 3 Falcius and 3 Pax. Falcius helps you make better trades and hence establish firmer board control. Pax summons dervish tokens early on, and they are devastating with Fireblaze Obelisk. If you’re playing a Obelisk oriented deck, you would need Whisper of the Sands also.
If you’re looking foward to craft legendaries, you have four choices: Inquisitor Kron, Aymara Healer, Nimbus, and Zen’Rui the Blightspawned.
I would recommend Kron over Aymara, because it is a neutral Legendary, so that you could use him in other factions also. Aymara is pretty close to Kron. Nimbus is good too, but it is a bit too slow. Since you’re playing a budget deck, I assume that your game ends rather quick - one side or another. Kron summons a token immediately after you place it (unless you replace into Kron) and is a provoke body itself, while Aymara’s impact is greatly reduced with a single dispel, and Nimbus takes three turns to have her effect kicking in (1st turn you place her, 2nd turn you attack with her so she spawns an Obelisk, and on the 3rd turn the Obelisk summons a Wind Dervish).
Zen’Rui could be situationally good. You could steal stuff from generic 2 drops like Healing Mystic, to other greater threats like Lantern Fox and Kelaino. It’s a 3 mana body + removal + summon another smaller body, which sounds good on paper. However, when you have nothing to steal, Zen’Rui is a dead card.
I’m no expert in Vetruvian - there are a lot of ppl much better than me. Nevertheless, if you could upload your decklist here so that ppl from the forum can give more detailed advices to you (a lot of ppl use www.manaspring.ru to upload decklists, but I have never tried it before).
P.S. Just in case you missed this, Duelyst has a giveaway campaign via Humble Bundle. Google it up and you could get a legendary card Keeper of the Vale for free. If you’re new enough (joined after 15Sept) you could get free 20 packs also. You probably have known that already, but just in case you missed that great deal I’ll leave this note to you.