I believe cantina energy is much better used to farm the many important toons available only here - Lando, TFP, Wedge, Anakin, Aayla, Kylo all are must haves for haat raid and generally considered among the strongest toons. B2 is strong in Arena against tanks and buffers, GS and JC are good pilots.
For mods with good speed secondaries (this actually is the meta in this game) I look in mod shipments to buy for credits and usually buy one between Credit Heists. I just bought a 3 dot gold mod (not so much potential but a lot cheaper than 5 dots), and speed improved two times to 10 in a slot where I didn't have many speed (now 16, 10, 9 and 7 available here, the 10 helped a lot and improved speed of one Arena toon by 7).
The amount of Cantina energy needed to find a 3 to 5 dot blue, purple or gold mod with pre-set speed secondary is so staggeringly high, it's just a better investment in must-have toons.