Minimize loop areas: Keep the current paths of high-frequency and high-current components, such as switches and inductors, as short and as close to each other as possible to reduce the loop area and hence, minimize the radiated fields.

Ground planes: Use a solid ground plane under the high-frequency components and signals. If your design involves multiple ground planes, ensure that these planes have sufficient stitching vias to maintain a low impedance path between them.

Decoupling capacitors: Place decoupling capacitors close to the high-frequency components to minimize EMI. The capacitors should have low ESR and ESL for better noise reduction.

Filtering: Use LC filters or ferrite beads for sensitive analog lines, reference voltages, and clock signals.

Differential signaling: Differential signaling can be used for high-speed or critical traces. It helps in rejecting common-mode noise and reduces EMI.

Good layout practices: Separate analog and digital grounds, use guard traces, and minimize parallel high-speed traces to avoid crosstalk. Keep the traces for different parts of the circuit separate and avoid unnecessary routing under sensitive components or traces.

Shielding: If needed, use shielding measures like metal enclosures or shielded cables to reduce EMI in critical sections of the board.

Texas Instruments BQ25570: This is an integrated energy harvesting nanopower solution that features a low-power Buck-Boost converter with maximum power point tracking (MPPT). It also supports charging of energy storage elements, such as supercapacitors and batteries.

STMicroelectronics SPV1050: This is an ultra-low-power energy harvester and battery charger with embedded MPPT and power management functions mainly targeting small solar panels. It can also be used with thermoelectric generators (TEGs).

Analog Devices ADP5091: This IC is designed for photovoltaic and thermoelectric energy harvesting applications. It is an integrated boost and buck converters with MPPT and has a maximum power point tracking function and flexible output voltage regulation.

U1 (AEM10941) - Unfortunately, this IC is central to the design and is application-specific. Therefore, finding a direct cost-effective replacement might be challenging. But you can still check distributor websites like Digi-Key, Mouser, or Arrow for pricing or quantity price breaks. For alternative energy harvesting, ICs consider products from Texas Instruments or Analog Devices that might be more affordable.

LBUCK, LBOOST - Inductors can vary widely in cost depending on tolerances, Q-factor, and other factors. Look for inductors with a similar inductance value, current rating, and footprint from reputable manufacturers like Würth Elektronik, Coilcraft, or TDK. You can check pricing and availability on major distributor websites to find cost-effective alternatives. Be mindful of the trade-offs, such as size, self-resonant frequency, and efficiency, while selecting a cost-effective substitute.