I was exactly like you a few months ago as a matter of fact I was extremely nervous about getting Coco neutered but finally I did. He got neutered at 6 months. Everything went extremely well, he's still his old hyper self lol, although you can tell a difference, for instance when I train him he's much more focused compared to how he used to before when he wasn't neutered. He doesn't hump anymore and doesn't mark either.
The clinic had charged me 200$ including pre-op blood test and the operation itself. Oddly enough my vet didn't prescribe any pain meds although Coco seemed to be well he didn't look like he was in pain and surprisingly was back to himself in just a day! I guess it depends on the dog but talk to your vet before the procedure and he'll be able to specify all the information according to your pup's needs
Let us know how it goes!!
Good luck