Optimization paradox: The cheapest route often isn't the fastest, and the fastest isn't the cheapest. Adding more variables (comfort, safety, number of transfers) creates exponentially more combinations to evaluate. At some point, calculation time becomes impractical.

What comes closest?

Rome2Rio: Shows multi-modal options with rough pricing, but doesn't optimize for cheapest routes. It's more of a discovery tool showing what's possible rather than a booking engine.

Kiwi.com: Focuses on flights but includes some bus and train connections. Their "nomad" feature finds cheap routes with multiple stops, though it's not truly multi-modal beyond flights.

Omio (formerly GoEuro): Compares trains, buses, and flights within Europe, with actual booking capability. This is probably the closest to what the traveler wants, but it's limited to Europe and doesn't include rideshares or ultra-budget options.

Google Flights + manual research: Many experienced budget travelers use Google Flights to find cheap flight combinations, then manually search Flixbus, BlaBlaCar, and regional train websites to fill gaps. It's time-consuming but currently the most effective approach.

The real strategy for ultra-budget travel:

Think in regions, not direct routes. Instead of Norway to Turkey, find the cheapest flight from Norway to anywhere in Central Europe, then the cheapest onward option from there. Breaking routes into segments often reveals cheaper combinations.

Be flexible with timing. Many budget travelers don't book everything upfront—they book the first leg, then search for onward options from wherever they land. This requires flexibility with schedules but finds opportunities that fixed-date searches miss.

Use regional specialists. Europe has Omio and Flixbus. Southeast Asia has 12Go.asia. South America has ClickBus. Learning regional platforms gives access to options that global search engines miss.

Join budget travel Facebook groups. Experienced shoestring travelers in groups like "Budget Backpackers" often know obscure routes and carriers that don't appear in search engines. Someone who's done Norway to Turkey overland can share exactly how they connected each segment.

Consider travel time value. A route that saves $50 but adds 20 hours might not be worth it, depending on your situation. If you're traveling to a job interview, obviously not. If you're on a six-month backpacking trip with no schedule, maybe it is. Build time value into your decision-making.

The philosophical question: Would you actually want this ultimate budget search engine? The cheapest route might involve sketchy overnight buses, illegal taxi shares, and hitchhiking segments that come with real safety concerns. There's a reason most search engines don't surface these options—they involve risks that companies don't want liability for.

Part of budget travel's appeal is the problem-solving and local knowledge gained by figuring out these connections yourself. Arriving in Budapest and asking hostel staff about the cheapest way to Belgrade often reveals options no algorithm would find—and leads to the conversations and connections that make travel memorable.

The best travel isn't about the destination—it's about what you learn along the way. That includes learning to navigate complex transportation networks, make smart tradeoffs between cost and convenience, and occasionally embrace the chaos of plans that don't work out as expected.

So while the ultimate ultra-budget multi-modal route optimizer doesn't exist, the tools and strategies to find crazy-cheap travel routes do. It just requires more creativity and patience than typing in two cities and clicking "search." For true budget travelers, that's not a bug—it's a feature.