First off, CAMP budget doesn't increase as you level up. I'm not sure how that rumor started, but it's completely untrue.
Second, make sure to check the "stored" tab to see if you have random crap taking up budget space. Scrap anything you don't actually need. If you scrap a blueprint it'll break it down to all the individual walls, floors, etc again so you can rearrange them or scrap what you don't need.
Other tips:
each turret takes up roughly 10% of the budget, and they're generally worthless for anything other than level 5 mongrels or ghouls, so don't bother building them.
This resource map shows all the mineral, acid, and junk nodes on the map. If you build near one of them you'll automatically learn how to build the extractor for that resource. If you constantly find yourself running low on a particular type of scrap this is a great way to help solve the issue.
If you don't need a resource node, try to find an area with ample water. Take the budget you saved by getting rid of your turrets and set up a purified water and adhesive farm. pure water sells for 5 caps each, and bulk adhesive (10 adhesive and 1 plastic) sells for 15-20 depending on your charisma and perks.
