I just heard about this post, so did a quick search and currently it looks like Sriko is the only company providing affordable sodium-ion batteries. They appear to be within about half the energy density of lithium-ion batteries. I used AI (first Google then Bing because it has ChatGPT 5) to create tables comparing battery types:

  A($/Wh) D(Wh/kg) D(Wh/L) P($)  E(Wh) M(kg) Vol(L) V(V) C    S     URL(Sodium-ion)
  0.46    97.50    235.79  1.81  3.9   0.04  0.017  3.0  3000 18650 https://srikobatteries.com/product/sodium-ion-18650-3-0v-1-3ah-3-90wh-20c-rechargeable-battery/
  0.34    114.29   258.31  3.23  9.6   0.084 0.037  3.0  3000 26700 https://srikobatteries.com/product/sodium-ion-26700-3-0v-3-2ah-9-60wh-3c-rechargeable-battery/
  0.32    134.78   258.89  9.98  31.0  0.23  0.120  3.1  5000 33140 https://srikobatteries.com/product/sodium-ion-battery-33140-3-1v-10ah-31wh-12c-cylindrical-battery/
  0.40    112.50   224.09  21.85 54.0  0.48  0.241  3.0  5000 46145 https://srikobatteries.com/product/sodium-ion-46145-3-0v-18ah-54wh-10c-rechargeable-battery/
  0.20    122.22   231.09  43.70 220.0 1.8   0.952  3.2  5000 pack  https://srikobatteries.com/product/sodium-ion-na-5c-70ah-220wh-battery/
  
  C($/Wh) D(Wh/kg) D(Wh/L) P($)  E(Wh) M(kg) Vol(L) V(V) C    S     URL(Lithium-ion)
  0.23    252.00   761.77  2.85  12.6  0.05  0.017  3.6  300  18650 https://www.18650batterystore.com/products/samsung-35e
  0.16    262.01   742.41  2.85  18.0  0.069 0.024  3.6  300  21700 https://www.18650batterystore.com/products/samsung-50e
  
  O:   outlay
  D:   density
  P:   price
  E:   energy
  M:   mass
  Vol: volume
  V:   voltage
  C:   cycles
  S:   size
  
  Note: 26700 is not the same as 27100, they are just what each site specializes in.
  Comment: I think that it should have been 18065 instead of 18650 because then the last 3 digits could be length in mm, same for the others, but what do I know.
  Edit: I forgot to add cycles. When considered, they drop the price of sodium-ion to roughly 5-10 times less than lithium-ion for the batteries shown here.