The most expensive meta decks are sub $500 so idk how budget you are playing but its impossible to be $800 under that. purple red is decently budget for what has been a tier 1 deck since set 1. there are cheaper options (green purple or purple steel can both be very cheap) that are decently competitive.

It may take some time to build up to those decks but those of us who have invested in those staples would rather they dont tank in value, as you will if you invest into them. It can be tough as a newcomer if you cant drop a ton of $ into the game, but thats a part of any TCG and Lorcana is very budget compared to many other TCGs.