I did this on an old Hilux I had back in the day. All I did was lop off from the muffler back, added a dual exit muffer and piping. I did it on the cheap so it was about $100. It was loud which I did not mind BUT it would not pass smog because the machine could not pick up emissions. I had to plug one side to get it to pass finally. My next mod is to swap the muffler, but I am SO very leery about drone.
should cost about 300 to do. just buy a 2 outlet muffler & have a shop fab the piping. dont be surprised if u dont have the stock sound after getting a different muffler tho.
thats why i said buy the muffler first, the rest is pipe cost & bending , then labor. but it may cost less in ur area of the country. like u , i thought that was alot so i just bought the whole thing & installed myself.
300 bucks is a good overall estimate. you have a ton of choices of mufflers that are one in and two out. you might also have a choice of materials used from the piping to the hangers and tips. I would say look up youtube and listen to exhaust sound clips to have an idea of which one to go for and just make a get it done.