If you are playing with a group constantly, you will be alright. You might be a bit of a weak link, but you should be alright. Keep in mind that you can always drop a forma in a fully leveled item to add a polarity slot to it, which cuts the cost of any mod with matching polarity in half. Can be a useful alternative (or addition) to a catalyst or reactor.
That all said, if you find yourself playing this pretty often, and you have some go-to equipment already, the benefits of the catalysts and reactors quickly outweigh the cost.
I suggest trying to earn them through the alert blueprints, rather than platinum, if possible. By the time you really will get the full effect of the items, you should have plenty of resources to spare on crafting them.