I generally agree, there’s always someone willing to "help you" for 25-35K baht with something at an actual cost of 1900 baht. I would never use agent myself either.
But, a border bounce cost between 3-4K baht including everything and it guarantees you an additional visa exemption. I think that’s a reasonable price for something you in fact sometimes can’t do on your own.
If you hold a passport from GB or Ireland you don’t need a visa for 90 days as Stepehen explains. Just get a cheap ticket out within the initial 60 days if you’re airline ask for it.