Hi! I tried out a deck like this for a while and it's a blast! unfortunately, my local meta had a lot of graveyard hate in it, so it didn't really get to go off very often, but now that dredge isn't as big a deal, this seems like a sweet choice!
I know you said you don't want to spend a lot on lands, so looking past that, there are some sweet, cheap cards that can make Sidisi even stronger.
Thought Scour and Grizzly
Salvage are awesome, since they can trigger Sidisi and both replace themselves. And since you're feeding your graveyard,
Tasigur, the Golden Fang, or
Gurmag Angler are all stars. They dodge
Lightning Bolt and
Fatal push, and Tasigur has never been easier to activate than it is in a Sidisi Deck.
Finally, if it's in your budget,
Grim Flayer is better than
Tarmogoyf in a deck like this.
Hope this gives you some ideas! Good luck