[It used to be under $100... it's not too far above it now, but I've been stubborn about pullng out the most expensive cards, because they do so much in the deck.  Oy.]

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I don't think this deck needs too much explanation... it's a build that's purposely limited to $100 (our play group's challenge), and it's primarily filled with creatures that ETB with +1/+1 counters natively, and that have death or ETB triggers, plus a bunch of sac outlets and other cards with death triggers.  Add in Marchesa, and you can sacrifice creatures that ETB with +1/+1 counters on each player's turn, bringing them back at the end as untapped blockers for the next turn (then rinse and repeat on every player's turn, racking up tons of death/ETB triggers).  Any creatures that don't naturally put +1/+1 counters on themselves have plenty of other ways to get a +1/+1 counter (many at instant speed).  Having your creatures ETB with +1/+1 counters also alleviates your need to abuse dethrone and primarily attack the player with the most life, which will change the dynamic of how everyone else reacts to your shenanigans.  And being able to attack anyone you want lets you dictate your own game plan better.  Relying on dethrone means being an aggressive attacker in predictable ways, but if you should have the most life, your shenanigans are shut down, and you're target numero uno.  Playing the deck without abusing dethrone makes you less of a threat that needs to be dealt with ASAP.

One dynamic to point out is that this deck thrives on its ability to sacrifice your creatures at instant speed to avoid them being targeted in any way you don't like.  That means a pesky Path to Exile directed at any non-Marchesa creature is easy to sacrifice to an outlet (10+ of them) and get back at the end of the turn.  The trick is when they target Marchesa... you have to decide whether you are going to sacrifice all your other creatures before Marchesa leaves play, or risk them staying in play and potentially getting removed.  Obviously, you sac them all before Marchesa, leaving one last sac outlet for Marchesa (since she triggers herself).  Let your opponents board wipe away.  Since we can put +1/+1 counters on all our creatures so easily (not requiring an attack phase), we can sac them at will, on each player's turn.  Once our board state is achieved, it get pretty OP.  The sac outlets are critical, and most of them are very difficult to get rid of (they get +1/+1 counters or get indestructible when they sac a creature). 

My playgroup went overboard reacting to this deck's first couple games... they all added a bunch of graveyard hate, and another guy told me later that he avoided building his Desert landfall deck because of all the added grave-hate from Marchesa!  Ha!  And all this from a fairly unadjusted <$100 deck!  But now she's been more adjusted, albeit the tinkering never stops.  [And now she's a touch over $100, too.]

Another good thing about not relying on Marchesa's dethrone mechanic, and not needing to attack the player with the most life in order to get +1/+1 counters on your creatures, is that you get to run life gain, which is a pretty huge deal.  Relying on dethrone means no life gain shenanigans, because you need to have an opponent with more life than you, and attacking them means they probably won't have the most life for very long.  It's dangerous to run life gain while simultaneously trying to rely on Marchesa's dethrone to keep an engine running, which means you are always susceptible to a big hit putting you within striking distance of death.  Being able to safely run life gain and maintain your sac engine shenanigans is a big win!

The biggest question of a build like this is where to put your money...?  First, it's important to recognize how cheap this deck can be built with high synergy cards that do a lot in tandem with Marchesa, but are very cheap to buy.  That being said, Marchesa is tri-color, and the better the lands, the faster the deck, so I'm thinking that's my focus: build cheap and efficient everywhere else and invest in the lands.  It already has enough good ramp and draw to explode cards out, so a solid mana base that can ETB untapped could make it a lot more competitive.  If you wanted, you could certainly go cheaper on lands and swap a few cards into other slots that cost more, and help the deck more.  It's up to you.

(Keeping it under $100 over time might prove to be an interesting task... but this list will get updated as I swap out cards in an attempt to keep it cheap.)  [Ha!  Well, no more...]

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One thing I dig is the synergy between Marchesa and the graft mechanic. As creatures ETB, move +1/+1 counters from, say, Novijen Sages onto those creatures so they can be revived from a sacrifice, leaving one counter on the Sages. At the end of the second main phase of every turn, you sacrifice each of these creatures to a sac outlet, then when they return at the beginning of that end step, have Novijen Sages ETB first, then each of the next three creatures gets a counter from it. The next turn you do the same thing. On each player's turn, you get death/ETB triggers and the creatures enter protected by the +1/+1 counters and Marchesa. Cytoplast Manipulator, Helium Squirter and Vigean Graftmage are the other graft cards in grixis. All four have high value in this Marchesa deck and are not an option to take out, in my opinion.  So consider them that important to add if you end up copying this deck concept.

Jar of Eyeballs is sneaky good in here, primarily because it lets you put all the cards you looked at on the bottom of your library in any order.  Say you have 80 cards left in your library... you need to have creatures you control die 40 times, which sounds like a lot, but with four players if you sacrifice five creatures on each player's turn (which isn't a far-fetched reality), after two complete rounds of turns you'll have eighty counters on the Jar.  Four crits a turn will get you there in three rounds of turns.  Then you're reorganizing your whole library.  And you aren't sacrificing the Jar, so you can potentially use it again if someone forces you to shuffle your library.