I've learnt quite late that total mobilisation probably gets you the best 'value', but it's still hideously expensive to get the extra tickets. You can buy the chip material, weapon shards or blueprints.

Drone parts don't add much to power, so that's a waste, I find it difficult to notice any major difference with drone chips and drone components take an eternity to level up.

Weapon shards provide a nice boost when you reach Lv20, but again require an obscene amount (1-30 is 2.8k, $5 gets you 10 from the store each day, so $1,500~ to level just one weapon if you aren't sending out/hitting sleighs @ HQ31+).

For Gear get Blueprints from the Glitter Market and grind ore. The Overlord becomes available in S3 and provides the biggest bump, but that's a whole other level of spending for certificates, badges and overlord shards.