Have you been playing both characters? Playing one character benefits the other one, making it much easier to progress. If you swap between the characters often, you should be able to afford more than just one equipment per run.
There is currently a difficultly spike while playing Stan at around level 600, but other than that the game should be smooth sailing.
Join the Discord: https://discord.gg/WtKweNpdYp! There's a strategy channel you can use to get help with progressing.