I would suggest going to a few spa/hot tub dealers and talking with them. Don't get roped into having to use 7 - 8 different chemicals either. When we first got our hot tub we were using 6 or 7 different chemicals but after shopping around, we now only use 2 plus adjusting the ph if necessary.
We use shock on a weekly basis, potassium peroxymonosulfate each time we use it and adjust the ph weekly if needed.
You may also see if the previous owners will leave you their remaining old chemicals or at least the names of them.