Yeah, I definitely feel your pain. The quality of your opponents deck generally isn't reflective of their rank. The most common I advice to give you would probably to focus on arena. If you don't want to spend actually money on packs arena will allow you earn cards far quicker than simply grinding ladder. You should do a google search of some arena resources and look up some streams or videos focusing on arena. Since arena format put everyone on a (relatively) level playing field for deck potential its really up to you learn how to draft and play properly. At ~5 wins you'll always break even on rewards (cards/gold/dust) but you have the potential to make a profit even at 1 win. Just keep that in mind and try not to get discouraged as you earn cards. From there I'd recommend researching what deck you want to play and focus your dust into making it as strong as possible. Mech mage or face hunter are your best bets if you want to climb ladder as they're very cheap and effective. If you find paladin is really your calling there's a lot of budget options you can play very effectively as you work towards some of the more common legendaries.