First things first, autocarding (and a little reorganization):
Creatures 20
4x
Inventor's Apprentice3xany good 1 or 2 mana red creature aggro plays that I can buy for cheap at the shop
4x
Champion of the flame4x
Valduk, Keeper of the Flame2x
Traxos, Scourge of Kroog3x
Zahid, Djinn of the LampEquipment/Enchantments 12
4x
short sword4x
honed khopesh2x
cartouche of zeal2x
curious obsessionProtection 3
3x
dive downRemoval 4
4x
lightning strikeLand 21
as many ETB untapped UR sources as I can find(8)
Enough islands to reach 9-10 sources
rest mountains.
Maybe a desert?
It looks like you have a solid base here for a budget deck. I like it. I'll try to keep my suggestions on the cheap end and common/uncommon if possible.
For your creature slot I see three reasonable options at common/uncommon:
Goblin Trailblazer because it has menace, so if you suit him up and they block him, not only are you soaking 2 blockers but they may have to throw something that you can kill in front of it.
Rigging Runner because first strike and power buffs are great together
Sun-Collared Raptor because it has trample and is a mana sink. The threat of activation is very real mid-combat.
If you can find them for cheap I would recommend the following rares over any of the commons/uncommons:
Kari Zev, Skyship Raider ($1) is just SUPER hard to deal with having, menace, first strike, and another body on the attack. Giving her equipment just makes her doubly dangerous for the same reasons as both Goblin Trailblazer and Rigging Runner.
Earthshaker Khenra ($5) Getting a blocker out of the way in the early game and then being a mana sink later is a good quality. Now I don't think the Earthshaker is as good in your deck as it was in the old Ramunap Red decks, in fact I think it may even be worse than Kari Zev, but I just thought I'd point it out.
Lands:
Unfortunately your only options for ETB untapped U/R lands are rares:
Spirebluff Canal currently sitting around $9 a piece
Sulfur Falls $6 each
Spire of Industry $3 each
Obviously Spire is the most budget friendly, but I'm not sure how consistent it will be for your deck. You could probably run at least 2 of them though is what I'm thinking.
Technically there are common filter lands that enter untapped however I don't know if your mana base can support those considering how few lands you have.
But for reference I'm talking about things like:
Aether Hub down to $1
Painted BluffsSurvivor's EncampmentUnknown ShoresCrypt of the EternalsFor the sake of completeness your etb tapped U/R land options are:
Highland LakeUpgrade:
I know it's rare and slightly higher casting cost, but I'd consider a pair of
Captain's Hook ($0.50) over two of your other equipment, just to give you something to attach that has a little more oomph to it.
Looks like a sweet budget deck.