Painter's Grindstone

Not a bad budget version of the Painter-Grindstone combo. Try Chill maybe? if not just for sideboard

I'd drop the Isochron Scepter and Two tops. Since you're running Red you could run 4 Lightning Bolts. Main decking 4 blood moons is crazy, but it does work in Legacy. I'm not sure why you are running Red... people run Red for Imperial Recruiter in Painter, but that card is not exactly budget. Maybe you should run White/Blue for Enlightened Tutor.

Roughly 3/5 starting hands I could get the combo off by turn 3-4. According to this site anyways, and assuming the opponent doesn't try too hard to stop it.

If ur running red u could always use faithless looting for card draw.

Its always nice to see Painter decks, Painter is the deck that started me off in Legacy. Making it super budget is getting sort of hard though since a lot of cards have jumped up in price over the last couple years.

I'll start off just trying to give some constructive criticism of some of your decisions and which cards I think should be replaced. Keep in mind here that I'm looking at the overall Legacy card pool and what cards are just more efficient than others, all judgements should be made based on the decks people around you play and what works best against them.

Power Artifact just doesnt add very much for you. The infinite mana loop is cute, but its just unnecessary. The entire combo here costs 6 colorless mana. If you already have a Monolith, and 2 blue mana to cast Power Artifact, thats already 5 mana. You will find yourself cursing this card when you top-deck it.

Isochron Scepter really doesnt help you much either. I get why you want it, but its just not going to help you against a serious deck. Playing a card that lets you cast Counterspell next turn is just not where you want to be, especially in a format with Abrupt Decay. The ease with which you can get 2 for 1'd on Iso-Scepter without actually accomplishing anything is a serious issue for the card.

There are some other cards I'll come back to, but those two are both easy cuts as they dont really align with the rest of the deck that well.

I'll try to jump into budget suggestion mode now:

Goblin Welder. Its a major benefit of playing red. Have two Grindstones but your opponent already managed to kill your only Painter? Its back now! Need some mana but you already used your Grim Monolith? Swap it into the graveyard end of turn and then back into play during yours.

A Wurmcoil Engine in the deck with Welder also enables a grindy alternate win-condition. (non-budget aside: Transmute Artifact on Grim Monolith into Wurmcoil Engine is a fun interaction, and Transmute Artifact is much better than Fabricate)

Now the issue of consistency. I think you need more library manipulation. Without it you might as well just not play blue at all and go all in on Moon effects instead. If you had blue fetchlands, I would say Brainstorm. But staying on a budget, Preordain would be a good choice. Thirst for Knowledge may be a better overall card for you than Fabricate. Especially if you have Welder to use any artifacts you pitch in the graveyard.

I'd also suggest Ensnaring Bridge and Spellskite somewhere in the 75. And you just need to have something sideboard to deal with Emrakul triggers. Betting on 3x Surgical Extractions isnt going to be good enough. Something like Tormod's Crypt is just going to be a lot easier to work with and its an artifact.

As for splashing a color, if you think your manabase can support 3 colors, I would go with black over white. Enlightened Tutor isnt bad, but Tezzeret, Agent of Bolas gives you a lot more options. It digs for cards, makes blockers/attackers, and can randomly win the game with his -4. Baleful Strix is also a decent card.

I actually have a (definitely not budget at all) Grixis build that I've been tuning, though it focuses less on the Painter angle since thats not a guaranteed win against certain decks. The specific cards probably wont be that helpful to you working on a budget, but some of the interactions are worth considering as they can often be mirrored on a less efficient budget scale.
http://www.mtgvault.com/tal/decks/transmute-artifact/

Also, while working on Painter, keep in mind that the deck you originally cloned here is an attempt to make a budget version of a very specific Legacy deck called Imperial Painter. A lot of that deck's design revolves around getting a turn 1 Blood Moon effect as often as possible. Against a lot of Legacy decks, Blood Moon can be essentially a win condition, but against many others it is not. Make your decisions about it depending on what types of decks people around you play.

Hopefully you find something in this massive wall of text helpful or informative.