Depending on the connected load of the hot tub; i.e. electric heaters, it may require up to a 60A., 220V. GFIC protected, hard wired not outlet, service. Don't want any children lit up or adults for that matter.
Seems like everyone has a brother-in-law or cousin that is a 'electrician'. Of course that BIL or cousin may work at the utility company, or automobile plant, or wire airplanes--and they are not qualified electricians. Get a licensed contractor to look at the work. That contractor will then have a licensed electrician do the work. BTW, ask the electrician for his license, he will be happy to show the license. Peace of mind that my house will not burn nor any of my children will be electrocuted is worth the cost of having a professional do the work.
Back to the original question of the cost--its impossible to estimate costs without visiting the site and considering all the conditions. Estimates are free and the way work is right now I believe a contractor could come right out.
This is the smartest answer Yet.
I am a licensed electrician and make a good living reworking the nightmares that the BILs or homeowners do themselves. If you have to ask how , call a pro for an estimate. Ask for references even on the "pros" as some of those are idiots.