Hence why I was thinking the OP is a troll.

I charge $1k/day on side work these days, laborers in my area charge $500. When people balk I usually say "you can grab two guys from home depot and wing it. Perhaps you'll save money" I don't even mean it jokingly, those homedepot guys are pretty dang good.

Agreed on the 1-2 day estimate.  I usually push long and get it a house done in 10-14 hours.

Calculate the time you need to get the job done to expectation. Assess the cost & maintenance of the tools you will use (all pro-rated to the # days used: car to get there; gas; car insurance; laser; tape; cad; computer; ladder; camera; backup hard drive for e-data; scans for existing docs; drafting time for existing docs; etc…). Determine a reasonable hourly rate (not min wage & not exhorbitant, but something that would pay your rent/food if it produced 40hrs/wk regularly). Apply it. Re-do your math if the gut check total doesn’t feel appropriate. Don’t try to compete with anyone. This is you & your efforts.

If you mess it up & are too low, hold your number and own it as a learning experience on this first one. Once you have done a few and can reflect back on exactly what was hard and what was easy, then you can be more precise in your estimates for clients.

In your estimate of hours, add around 20% for float especially if your hourly rate is lower than the average or median rate. The reason for 20% is similar to contingency. It is called float. There are variables you can't assume to know precisely. Now, you can also offer a base estimate with a gmp (allows you a little more flexibility in case hours exceeds the base estimate but up to a higher amount but reasonable. If you know what amount of time others take and their rate, you can estimate more hours with a lower rate because it is a new task for you or you charge the rate to that estimated hours and chalk up extra hours you spent as cost on you for learning something that you otherwise should have already known before you offer such services to clients so the client isn't paying for your... well... slowness. Your market competitors are professionals that knows what they are doing. You are kind of starting out. You don't bill your clients for you learning to do the job on their dime. Clients expects every person who offers to perform a service to be able do it. They expect the lawnmowing service person to know how to mow the lawn and how to operate a lawn mower. Right. You also need to use the right tools for you to do this. Running measuring tapes over long distances would be handy to have a second person but if you have tools that you can use to do the measurements with accuracy without requiring a second person, all the better. With some money investment, getting a LIDAR laser scanner/camera or other similar devices or a method of doing photogrammetric modeling from cameras and maybe a camera drone and a few measurements for scale, may be of use to doing your work more efficiently with less hours (possibly but not a guarantee unless you know what you are doing) and be able to do a lot quickly. This stuff can be expensive and I think that it is partially intentional for a reason and limit number and units out there and the number of competitors to keep the number of competitors small if they can. Then those doing this should be able to make back their money.... right? Business? Right. Stop acting like you are not a business. If you charge people to do a service.... you are a business and engaged in commerce. Okay. So don't whore yourself out for peanuts when you can be earning an income. Be fair but don't be bending over backward to working like a sweatshop for effectively less money per hour than a Chinese sweatshop. So keep in mind, you didn't go to college and all this to live that lifestyle. Don't waste time on those types that don't want to pay and just want it all for nothing bullshit. However, have tools that allow you to be efficient with your time and able to do by yourself otherwise you need someone else on your team to assist and that comes at a labor cost. Two people on a site for the same duration of hours costs easily twice one person, right? That would drive the price you have to charge. This can be where you run into competitive issues.

Bottom line: The important thing is 1) Know what you are doing, 2) Have some float and possibly a guaranteed maximum price range up from your base estimated amount that will take into account some variables that you can't predict or know, 3) Invest in tools that will enable you to be efficient and competitive. The exact how is up to you.