Chroma is actually pretty easy to get, as long as you don't mind farming for an Ember helm, Saryn systems, and Frost chassis. The rest of the quest is pretty simple, and quite doable solo. Mesa requires more bs for her quest, as you need to get the Mutalist AladV coordinates, and then farm him. When debating spending play on a frame, my logic is to only buy those that are a huge hassle to get through normal playing. Kinda like how some weapons require a lot of bs to build, so a 50% off purchase coupon makes it easier to go that route. If you buy Mesa, check out the Gunslinger bundle, since you get the Redeemer (stupid fun melee), the Gammacor, and Paracyst, along with her.