Well, if you're long on money, you can buy a jig. If you're not long on money, spending a little time making some dovetails by hand (on the first 10 or so don't even make a bad box - just make the joint and cut it off, then make another one) and then moving on to making some boxes will mean that you never need to buy the jig, or take the time needed to set the jig up, or find the space to store the jig. It ain't rocket science, but it is a skill, and if you practice the skill, you get better at it. Storage boxes are excellent further practice once you'd done a few joints purely for practicing the joint with no consequences if you screw up. Plus, you can make dovetails by hand which routers cannot duplicate (they need fat pins, because the router bit needs to be able to hold together - by hand you cut with a saw, and can make much skinnier pins).
As for woods, either your wood source is weird, or your location is screwing with the price of wood if any sort of poplar is expensive. Go with whatever is locally affordable or free. Hunt out sawmills for directly buying wood, or cabinet shops which may have "shorts and offcuts" for free, or at a low price.