Dino Deck with a scrap engine. Side options with Shaddoll engine when going second. MRT and Red Reboot for Trap Decks or decks that heavily rly on Spell/Traps. Exchangeable with Twin Twister or Cosmic Cyclone.
Other Extra-Deck options are: Topologic Bomber Dragon and Accesscode Talker, Zeus can be played instead of Evilswarm Night.
Other Side-Deck options are: Token Collector when playing against Swordsoul or Sky Striker.
BUT of course the best engine is Destroyer Pheonix Enforcer, but since this is meant to be a budget deck, it's not on the list.