One of the toughest aspects of creating Modern on a Budget content is creating an affordable manabase. Unlike Standard or Pioneer, you can get away with cumbersome tapped lands without falling behind. With Modern, the format is so blisteringly fast that playing off-curve can cost you games, depending on the strategy.
Instead, manabases that come in untapped often include a higher price due to their flexibility, which can be tricky for budget-players to acquire. Still, there are a few options in Modern which are budget-friendly and can provide the desired results.
In Modern, the formula for manabases rarely changes due to fetches and shocks becoming such a staple feature of the format. There are a couple of things to keep in mind when constructing an affordable manabase.
Preferred archetype: Aggro or Midrange
Like in Pioneer, this cycle is a personal favorite to include in budget Modern builds, because it allows two-color strategies while being kind to your wallet. At the expense of one life, you can reliably cast either of your colors or pay generic mana into a spell. In Modern, these are ideal placeholders on either horizon or shock lands given the accessibility and entering untapped.
The incremental damage offers an upside, too. This will help you understand how to manage your life total, which is a key aspect of the game. However, you don't want to run too many across various colors, as you will lose more life than you can pull back. These are ideal for aggro and midrange strategies. It gives you action throughout all of your turns. With this, pain lands should be an evergreen cycle within Standard—they fix your mana and they're already cheap!
Preferred archetype: Midrange and Control
While not as popular in Modern, check lands are an excellent option on a budget. From a budget viewpoint, they offer an upside which you will likely keep in your lists for some time, and only improve as more lands with subtyping are printed. Check lands perform better in higher land-count builds to offset the chance of coming in tapped. Control and Midrange archetypes are interested in particular as they are slow enough to benefit from either.
Even then, you can still use check lands alongside shocks to complement each other, granting better fixing. Check lands are the most underrated land cycle in Modern on a budget—they provide suitable fixing, require easy to meet criteria, and are affordable.
Preferred archetype: Aggro
Introduced in Zendikar Rising, the Pathway lands are not-quite-duals but offer interesting decisions without coming in tapped. I'm a big fan of this cycle and believe these to be more reliable than the fast lands from Scars of Mirrodin and Kaladesh. You'll want to run these in aggressive strategies such as Boros Hammer, Bogles and Izzet Blitz to ensure you have momentum in the early turns. Granted, these will see more play in a format without fetches, but these are still ideal on a budget.
Again, these port well into both Standard and Pioneer, which encourage mileage in your purchases. Also, Kaldheim will look to complete the cycle with the Golgari, Simic, Rakdos and Azorius pairings coming soon! My only issue with this cycle is these should not be at rare and would be an excellent option to have at uncommon. This is a classic example of oversaturating the rare slot with dual lands that are an essential aspect of the game. With the ongoing power creep in cards such as Veil of Summer and Mystic Sanctuary, it's possible to see functional dual lands at a lower rarity.
Preferred archetype: Control, Midrange, Aggro
It's impossible to discuss Modern manabases without bringing up either of these regardless of budget. Both shock and fetch lands are the gold-standard of Modern fixing that can limit your options if you are a format beginner. Naturally, you'll want to hold off on picking these up until you are comfortable and financially committed to playing Modern. However, there are a handful of archetypes that are viable without the versatile lands.
Izzet Storm is a fantastic example of raw power at an affordable rate. Storm omits fetch lands, as you want the scry from Serum Visions to stay at the bottom. You don't need shock lands either, because Spirebluff Canal and Shivan Reef provide smooth fixing to engage in the early turns.
With this, you'll want to hold off on picking up the enemy fetch land cycle. Why? They're seeing a reprint in Modern Horizons 2 mid-next year. More importantly, they'll be at rare, so circulation will hopefully drive the price down further. It's doubtful they'll be 'budget' but, they will at least become cheaper compared to the current pricing. Budget is about finding the right opportunity to pick up cards on the cheap, and it's worth waiting for Modern Horizons 2 to see if it's worthwhile for you.
Until then, it's sensible to pick up the ally fetch land cycle, such as Flooded Strand and Windswept Heath, to grow your collection. White-based fetches are often cheaper, given the color isn't as widespread in the format.
For example, in a Jeskai build, you can use Flooded Strand to grab either Steam Vents or Sacred Foundry without investing in Scalding Tarn. You're unable to search for the Mountain in your list, but you can still play around this and save money long-term.
It may feel intimidating to enter Modern with the idea of investing a huge amount of money in the manabase, but this is far from the case. You'll often see players highlight the supposed steep entry level as a way to deter new players instead of helping them. Either way, you can invest a low amount in the manabase and continue to play one of Magic's diverse formats.
It may limit the strategies you can play initially, but over time you can upgrade into other strategies which add mileage to your purchases. Understanding manabases and what you can afford is tricky, but over time you can amass an impressive collection allowing you to play whichever strategy you like. It's important to understand that you can take your time in upgrading or purchasing cards. Effects such as FOMO (fear of missing out) can manifest and create poor financial decisions, so it's better to remain sensible and accrue your cards strategically!