You will spend just as much, if not more money on laundry soap, dryer sheets, electricity and water, then gas or even more electricity to run the dryer every day several times to wash the sheets, blankets, mattress pad, pillows, etc...and they will wear out sooner so they'll have to be replaced. My time is worth something too and I'd rather be doing something fun instead of making a bed after doing laundry all morning every morning then perpetually making the bed.
The Pediatric Urologist my older grandson went to told us that it's often constipation causing night time accidents. The pooh lays on the bladder and it just can't hold it due to the weight pressing on it. He also said that limiting fluids doesn't work either due to the kids not having enough urine at once to signal the brain to wake up. They just kind of leak all night and don't just go all at once. Another thing is that getting dehydrated from limiting drinks is just not helpful either. Kids don't know how to tell us they are getting dehydrated. So just be aware of issues you can help with or cause to be worse.
Taking them to a doc won't hurt, it will only make you feel better about what you are doing.
Use night time pull ups and then let him pee before bed and let him sleep and know you won't have to do all that work every day. We use the dark blues ones from Huggies I think. They had Buzz Lightyear but now I think they have other characters on them too.