How easy is it to transition into consulting without an MBA from Columbia, Harvard, Stanford etc.? I want to get into MBB but can't afford a top tier MBA. Are there other schools that consulting firms recruit from? Preferably schools that do not cost an arm and a leg.

You can find this information easily from MBB's website - see their recruiting calendar to find where they visit.

And/Or simply go to your target school's website and see if MBB recruits from there. If you don't have a target school yet - visit Top 25-30 ranked school's website to see if MBB recruits

Good advice from Ayon. MBB definitely sticks to the top schools in general, but also pull from some lower-ranked schools like Emory. You can also search Linkedin for MBB employees who have MBAs, and see where they got their MBAs.